Abstract:
A method is provided for controlling a power sliding door system having a power drive mechanism for propelling the sliding door and a power latching mechanism for latching the sliding door in a latched condition. The methodology provides enhanced monitoring and control of the power sliding door system to improve the operation of the sliding door in both the power-assisted and manual modes. The control methodology inhibits the operation of the power sliding door system in response to the actuation of any of the sliding door handles or if a fuel door is in the path of the sliding door. The control methodology also inhibits the operation of the sliding door system if a child guard mechanism is enabled. The control methodology includes an obstacle detection routine which detects obstacles in two directions of travel. The control methodology does not require the power drive mechanism or inertia to cause the latch mechanism to latch the sliding door in the latched condition.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention generally pertains to motor vehicles and more particularly to a vehicle sliding door device. More specifically, but without restriction to the particular embodiment and/or use which is shown and described for purposes of illustration, the present invention relates to a method for controlling a vehicle sliding door device having manual and fully automatic operational modes. 
     2. Discussion 
     In various types of motor vehicles, including minivans, delivery vans, and the like, it has become common practice to provide the vehicle body with a relatively large side openings that are located immediately behind the front doors which are opened and closed with a sliding door. The sliding door is typically mounted with hinges on horizontal tracks on the vehicle body for guided sliding movement between a closed position flush with the vehicle body closing the side opening and an open position located outward of and alongside the vehicle body rearward of the side opening. The sliding door may be operated manually, as is most generally the case or with a power operated system to which the present invention is directed. 
     Commonly assigned U.S. Ser. No. 5,536,061, which is hereby incorporated by reference as if fully set forth herein, discloses a powered sliding side door for a motor vehicle. The door is operated with a power drive mechanism that is pivotally mounted on the door and extends through a side opening in the door. In the exemplary embodiment illustrated, the drive mechanism includes a reversible electric motor that drives a friction wheel which is spring biased to forcibly engage a drive/guide track located beneath the vehicle floor and attached to the vehicle body. The friction drive wheel rides on the drive/guide track to open and close the door and additionally guides and stabilizes its sliding movement. 
     While the arrangement disclosed in U.S. Pat. No. 5,536,061 provided certain improvements in the pertinent art, several drawbacks have been noted. These drawbacks included, for example, the appearance of the power sliding door, and the cost, reliability and performance of the drive apparatus. 
     Another type of power sliding side door utilizes a power drive mechanism having a reversible electric motor which is mounted in the vehicle body and connected to operate the door through a cable system. Such an arrangement is disclosed in U.S. Pat. No. 5,833,301. Another type of power sliding door utilizing a rack and a pinion gear to effect the movement of the side door is disclosed in U.S. Pat. No. 4,612,729. Arrangements of both of these types requires considerable accommodating space and modifications to the body structure and are not readily installed in an upgrading manner to convert an existing manually operated sliding door to a power operated sliding door. 
     Consequently, there remains a need in the art for an improved power sliding door system for a motor vehicle, and a method for controlling same, having improved reliability and performance which may be readily installed in an upgrading manner to convert an existing manually operated sliding door to a power sliding door. 
     SUMMARY OF THE INVENTION 
     It is therefore a general object of the present invention to provide an improved control methodology for a power sliding door system. 
     It is a more specific object of the present invention to provide a control methodology for a power sliding door system which arrests the operation of the sliding door system in a power-assisted mode when any of the handles of the door system are actuated. 
     It is another object of the present invention to provide a control methodology for a power sliding door system with enhanced child guard features. 
     It is another object of the present invention to provide a control methodology for a power sliding door system which arrests the operation of the sliding door system in a power assisted-mode when a fuel door is in the path of the sliding door. 
     It is yet another object of the present invention to provide a control methodology for a power sliding door system which detects the presence of obstacles in the path of the sliding door and inhibits movement of the sliding door in response to the detection of two obstacles. 
     It is a further object of the present invention to provide a control methodology for a power sliding door system which does not require the door drive means or inertia to actuate the latch mechanism and latch the sliding door. 
     A method is provided for controlling a power sliding door system having a power drive mechanism for propelling the sliding door and a power latching mechanism for latching the sliding door in a latched condition. The methodology provides enhanced monitoring and control of the power sliding door system to improve the operation of the sliding door in both the power-assisted and manual modes. The control methodology inhibits the operation of the power sliding door system in response to the actuation of any of the sliding door handles or if a fuel door is in the path of the sliding door. The control methodology also inhibits the operation of the sliding door system if a child guard mechanism is enabled. The control methodology includes an obstacle detection routine which detects obstacles in two directions of travel. The control methodology does not require the power drive mechanism or inertia to cause the latch mechanism to latch the sliding door in the latched condition. 
     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a vehicle equipped with a power sliding door system constructed in accordance with the teachings of the present invention shown incorporated into an exemplary motor vehicle; 
     FIG. 2 is a perspective view of a portion of the interior of the vehicle shown in FIG. 1; 
     FIG. 3A is a perspective view of the rear of the vehicle shown in FIG. 1 with the rear tailgate in the open position; 
     FIG. 3B is a bottom view of the light bar shown in FIG. 1; 
     FIG. 3C is a cross-sectional view of the light bar shown in FIG. 3B taken along the line  3 C— 3 C; 
     FIG. 4 is a schematic diagram of the vehicle shown in FIG. 1; 
     FIG. 5 is a perspective view of a portion of the vehicle illustrated in FIG. 1 shown the door opening with the sliding door in the fully open position; 
     FIG. 6 is a top view of the door opening of FIG. 5; 
     FIG. 7 is a cross-sectional view of the door opening taken along line  7 — 7  of FIG. 6; 
     FIG. 8 is a top view of the rack portion of the first guide rail illustrated in FIG. 5; 
     FIG. 9 is an enlarged view of a portion of the rack portion shown in FIG. 8; 
     FIG. 10 is a perspective view of the interior side of the power sliding door of FIG. 1 shown partially cut-away; 
     FIG. 11 is a top perspective view of a portion of the lower mounting assembly and power door drive mechanism coupled to the first guide track; 
     FIG. 12 is a bottom perspective view of a bottom portion of the lower mounting assembly and power door drive mechanism coupled to the first guide track; 
     FIG. 13 is a perspective view of a portion of the lower front corner of the door assembly shown in FIG. 10; 
     FIG. 14 is a top view of a portion of the power door drive mechanism meshingly engaged with the rack portion; 
     FIG. 15 is a perspective view of the rear of the power latching mechanism of the present invention; 
     FIG. 16 is a perspective view of the front of the power latching mechanism illustrated in FIG. 15; 
     FIG. 17A is a perspective view similar to that of FIG. 15, illustrated with the power drive assembly removed for purposes of illustration; 
     FIG. 17B is a perspective view similar to that of FIG. 17A, showing the actuation of the unlatching mechanism when the child guard mechanism is disengaged; 
     FIG. 17C is another perspective view similar to that of FIG. 17A, showing the actuation of the unlatching mechanism through the interior unlatch lever when the child guard mechanism is engaged; 
     FIG. 18 is a top view of the latch mechanism of the present invention with the cover removed; 
     FIG. 19 is a portion of the latch mechanism illustrated in FIG. 18 showing the relationship between the sensor arm and the pawl switch when the latch ratchet rotates the dog member to release the pawl; 
     FIG. 20 is a bottom view of the latch mechanism of the present invention with the base portion removed; 
     FIG. 21 is a side view of the latch mechanism of the present invention with the latch means in the fully open position; 
     FIG. 22 is a side view similar to that of FIG. 21, showing the latch means in the ajar position; 
     FIG. 23 is another side view similar to that of FIG. 21, showing the latch means in the fully latched position; 
     FIG. 24 is an exploded perspective view of a portion of the power drive assembly; 
     FIG. 25 is a top view of the first housing portion; 
     FIG. 26 is a bottom view of the second housing portion; 
     FIG. 27 is an exploded section view of the second member taken through its center; 
     FIG. 28 is a top view of a portion of the exterior and interior unlatch levers showing the first and second Bowden cables exploded from their respective cable retention means; 
     FIG. 29 is an end view of the exterior and interior unlatch levers shown in FIG. 28; 
     FIG. 30 is a top view of a cable and cable retention means constructed in accordance with an alternate embodiment of the present invention; 
     FIG. 31 is a top view of the power door drive mechanism according to an alternate embodiment of the present invention; 
     FIG. 32 is a portion of the power door drive mechanism shown in FIG. 31 with the drive clutch disengaged; 
     FIG. 33 is a portion of the power door drive mechanism shown in FIG. 31 with the drive clutch engaged; 
     FIG. 34 is a perspective view of the door panel of the present invention; 
     FIG. 35 is a schematic diagram in flowchart form of a first portion of the method of the present invention for controlling a power vehicle door; 
     FIG. 36 is a schematic diagram in flowchart form of a second portion of the method of the present invention for controlling a power vehicle door; and 
     FIG. 37 is a schematic diagram in flowchart form of the power door interrupt subroutine of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIGS. 1 and 2, a power sliding door system constructed in accordance with the teachings of a preferred embodiment of the present invention is generally identified by reference numeral  10 . The power sliding door system  10  is incorporated into a vehicle  12  illustrated as a minivan. However, it will be understood by those skilled in the art that the teachings of the present invention have applicability to other vehicle types in which a sliding door is desired. 
     With additional reference to FIGS. 5 and 6, vehicle  12  is shown to include a vehicle body  14  having a side opening  16  positioned on the right side of vehicle  12  immediately rearward of a forward door  18 . Side opening  16  is defined by an upper horizontal channel  20 , a lower horizontal channel  22 , a first body pillar  24  and a second body pillar  26 . Lower horizontal channel  22  includes a door sill  28  formed under the floor  30  of vehicle body  14  between a first sidewall  32  and a second sidewall  34 . Side opening  16  is adapted for receiving a sliding door  36 , with the sliding door  36  being slidably mounted on a first guide track  38  and a second, conventionally designed guide track  40 . While not illustrated, it will be understood that vehicle  12  may be equipped with a substantially identical power sliding door on the left side thereof. 
     With brief reference to FIG. 4, vehicle  12  is schematically illustrated and is shown to include an engine  42 , an automatic transmission  44 , a gear shift lever  46 , an engine controller  48 , an automatic transmission controller  50 , a body control module  52 , the sliding door  36 , a data buss  53  and a control module  54 . Data buss  53  interconnects engine controller  48 , automatic transmission controller  50 , body control module  52  and control module  54 . Preferably, data buss  53  is a J1850 buss which allows the controllers and control modules to share data on various vehicle dynamics. 
     Referring back to FIG.  1  and with additional reference to FIGS. 3A through 3C, vehicle body  14  is also shown to include a rear opening  55  positioned on the rear side of vehicle  12 . Rear opening  55  is defined by a second upper horizontal channel  56 , a second lower horizontal channel  57 , a first rear body pillar  58  and a second rear body pillar  60 . Second lower horizontal channel  57  includes a rear door sill  62  formed above the floor  30  of vehicle body  14  between a first and second rear body pillars  58  and  60 , respectively. Rear opening  55  is adapted for receiving a tailgate  64 , with the tailgate  64  being pivotably mounted to second upper horizontal channel  56 . Tailgate  64  includes a tailgate panel  65 , a key switch  66  and a light bar assembly  67 . Tailgate panel  65  is stamped from a metal material or preferably molded from a plastic material. Key switch  66  and light bar assembly  67  are fixedly coupled to tailgate panel  65 . Light bar assembly  67  includes a bar portion  67   a,  a pair of lights  67   b,  a tailgate handle switch  67   c,  a wire harness  67   d  and a resilient sealing grommet  67   e.    
     Bar portion  67   a includes a handle aperture  68   a  having an arcuate first surface  68   b  in the area across from tailgate handle switch  67   c  and a substantially flat second surface  68   c  in the area adjacent tailgate handle switch  67   c.  The configuration of handle aperture  68   a  creates an ergonomically shaped and positioned handle  69  with which to manually actuate tailgate  64 . 
     Tailgate handle switch  67   c  is fixed to bar portion  67   a  and extends into handle aperture  68   a  in a manner where it is substantially parallel second surface  68   c.  Preferably, tailgate handle switch  67   c  is a paddle-type switch which when actuated is operable for producing a tailgate switch output signal. The paddle-type switch is preferred in that it provides the operator of the vehicle door with the feeling that they are actuating a conventional mechanical door handle. 
     With reference to FIGS. 5 through 7, first guide track  38  is shown to curve inward relative to the interior of vehicle  12  as it approaches first body pillar  24  and generally follows the curved path of first sidewall  32 . First guide track  38  includes a channel shaped portion  70  and a rack portion  72 . Channel shaped portion  70  formed from a material such as steel, aluminum or plastic and preferably from a material such as nylon. Channel shaped portion  70  includes a first rear abutting surface  74 , a front abutting surface  76 , a plurality of mounting apertures (not shown), a plurality of generally rectangular tab apertures  80 , and first and second guide surfaces  82  and  84 , respectively. Channel shaped portion  70  is fixedly secured to second sidewall  32  and floor  30 , with a plurality of threaded fasteners (not shown). 
     Rack portion  72  is preferably formed from a Nylon material, but may also be formed from any other durable plastic material or metal. Rack portion  72  includes a second rear abutting surface  86 , a plurality of mounting tabs  88 , a dust lip  90  and a plurality of rack teeth  92  which collectively form a rack  94 , Rack teeth  92  extend through rack portion  72  along a bottom side  96  but do not extend through dust lip  90 . With brief additional reference to FIGS. 8 and 9, mounting tabs  88  are shown to be spaced along the length of second rear abutting surface  86  at predetermined intervals. Each mounting tab  88  includes a generally L-shaped projection  98  having a leg member  100  fixedly coupled to second rear abutting surface  86  and a base member  102  which is spaced apart from second rear abutting surface  86 . The tip  104  of base member  102  includes first and second chamfers  106  and  108 , respectively. A chamfer  110  is also included on the side of leg member  100 . Chamfers  106  and  108 , respectively. A chamfer  110  is also included on the side of leg member  100 . Chamfers  106 ,  108  and  110  aid in the assembly of rack portion  72  to channel shaped portion  70  by guiding each mounting tab  88  into its respective tab aperture  80 , as well as guiding base member. 
     With reference to FIGS. 1,  2  and  10 , sliding door  36  is shown to include a lower mounting assembly  120 , an upper mounting assembly  122 , a power door drive mechanism  124 , a power latching mechanism  126 , a hold-open latch, a handle mechanism  130  the control module  54 , a wire track assembly  132 , a plurality of interior switches  134 ′ and a door assembly  136  having a door panel assembly  138  and a trim panel assembly  140 . 
     Handle mechanism  130  includes an exterior handle assembly  142 , an interior handle assembly  144  and a handle switch  146 . Exterior handle assembly  142  includes an exterior handle  148  which is fixed to the exterior side of door panel assembly  138 . Exterior handle  148  is coupled to power latching mechanism  126  through a first Bowden cable  150  and is operable for unlatching door assembly  136  from first body pillar  24  to allow sliding door  36  to be moved from the closed position as shown in FIG. 1 to the open position as shown in FIG.  2 . In the particular embodiment illustrated, exterior handle  148  is operable between a retracted position in which first Bowden cable  150  does not cause power latching mechanism  126  to unlatch, and an extended position in which first Bowden cable  150  causes power latching mechanism  126  to unlatch. 
     Interior handle assembly  144  includes an interior handle  152  which is fixed to door panel assembly  138  and extends through trim panel assembly  140 . Interior handle  152  includes a release button  152   a  which is coupled to power latching mechanism  126  through a second Bowden cable  154  and is operable for unlatching door panel assembly  138  to allow sliding door  36  to be moved from the closed position to the open position. In the particular embodiment illustrated, release button  152   a  is operable between an extended position in which second Bowden cable  154  does not cause power latching mechanism  126  to unlatch, and an depressed position in which second Bowden cable  154  causes power latching mechanism  126  to unlatch. 
     Handle switch  146  is mechanically coupled to handle mechanism  130  and is operable for producing a handle signal that indicates that one of the exterior and interior handles  148  and  152 , respectively, have been moved from their retracted positions toward their extended positions. 
     Hold-open latch  128  is pivotably coupled to lower mounting assembly  120  and is operable for mechanically engaging first guide track  38  when sliding door  36  is positioned at the fully open position to inhibit sliding door  36  from closing. Accordingly, hold-open latch  128  may include a latching element (not shown) for selectively engaging first guide track  38 . Hold-open latch  128  is caused to release first guide track  38  through the operation of handle mechanism  130  or power latching mechanism  126 . 
     As best shown in FIG. 10, upper mounting assembly  122  is attached to an upper forward corner of sliding door  36  relative to the front of vehicle  12 . Upper mounting assembly  122  includes an upper hinge member  160  which is fixedly coupled to door panel assembly  138  and an upper guide roller  162  which is rotatably coupled to upper hinge member  160  and adapted for cooperation with second guide track  40 . Lower mounting assembly  120  is attached to a lower forward corner of sliding door  36  relative to the front of vehicle  12 . As best shown in FIGS. 11 through 14, lower mounting assembly  120  is shown to include a lower hinge member  168 , first and second lateral guide rollers  170  and  172 , respectively, a vertical guide roller  174  and a articulating head  176 . The articulating head  176  is pivotably attached to the end of the lower hinge member  168  by a pivot pin  178 . Articulating head  176  is generally U-shaped, having a pair of furcations  180  and  180 ′ which extend below lower hinge member  168 . Furcations  180  and  180 ′ each include a cylindrical aperture (not shown) for receiving a vertically extending roller pin  182 , each one of which journally supports one of the first and second lateral guide rollers  170  and  172 . A tongue  184  extends in a perpendicular direction between furcations  180  and  180 ′ includes a cylindrical aperture (not shown) for receiving a horizontally extending roller pin  186  which journally supports the vertical guide roller  174 . 
     The lower mounting assembly  120  is adapted for cooperation with the first guide track  38  wherein the vertical guide roller  174  contacts first guide surface  82  and first and second lateral guide rollers  170  and  172  contact second guide surface  84 . As such, cooperation between the guide rollers and their respective guide surfaces ensures proper vertical and lateral alignment of lower mounting assembly  120  to rack  94 . Since the articulating head  176  is pivotably attached to the lower hinge member  168 , rollers  170 ,  172  and  174  are capable of traversing the curved length of first guide track  38 . 
     A detailed description of wire track assembly  132  is beyond the scope of the present invention and need not be provided herein. Briefly, wire track assembly  132  is operative for providing electrical power from vehicle body  14  to sliding door  36  and, as shown in FIG. 10, includes a wire harness  190  having a plurality of wires which are enclosed in a limiter  192 . Wire harness  190  is operable for electronically coupling control module  54  and body control module  52  to permit the exchange of electronic signals therebetween, as well as for supplying electric current to power door drive mechanism  124 , power latching mechanism  126  and control module  54 . 
     Limiter  192  is comprised of numerous main track links  192   a.  Limiter  192  is described in more detail in commonly assigned U.S. Ser. No. 09/211,729, filed Dec. 15, 1998, which is hereby incorporated by reference as if fully set forth herein. With additional reference to FIG. 5, a plurality of protrusions  194  are included along the length of door sill  28  to assist in guiding wire track assembly  132  when sliding door  36  moves between the closed position and the fully open position. Insofar as the present invention is concerned, it will be understood that electric power is preferably hard wired from vehicle body  14  to sliding door  36  in such a manner. However, electric power may alternatively be routed to sliding door  36  through sliding contacts or other manners well known in the art. 
     Referring now to FIGS. 10 through 13, power sliding door system  10  is shown to include a power door drive mechanism  124  mounted within sliding door  36 . In the preferred embodiment, power door drive mechanism includes a power unit  200 , a flexible driveshaft  202 , a drive unit  204 , a drive clutch  206  and a drive pinion  208 . Power unit  200  includes a drive motor  210 , a gearbox  212  and a Hall effect sensor  214 . 
     Flexible driveshaft  202  includes a hollow non-rotating member  216  and a cylindrical drive member  218  which is disposed within non-rotating member  216 . Cylindrical drive member  218  is coupled to an output member of gearbox  212  at a first end and to an input member of drive unit  204  at a second end. Drive torque from gearbox  212  is transmitted from the gearbox output member through cylindrical drive member  218  into drive unit  204  where it is received by an input member (not shown). 
     Drive unit  204  and non-rotating member  216  are fixedly coupled to lower hinge member  168 . Drive unit  204  includes a torque input axis which is coaxial with its input member, a torque output axis which is coaxial with its output shaft  220  and drive pinion  208 , and a gear train (not shown) which is operable for changing the direction of the rotational energy between the input and output axes. Drive pinion  208  includes a plurality of spur gear teeth  230  which meshingly engage rack teeth  92 . As such, drive pinion  208  rotates when sliding door  36  is moved relative to vehicle body  14  or vice versa. 
     Preferably, drive motor  210 , gearbox  212  and drive unit  204  cooperate to provide drive pinion  208  with sufficient drive torque to enable sliding door  36  to operate while vehicle  12  is on 20% fore and aft grades with a velocity approximately 0.7 to 1.5 m/s. Drive clutch  206  is preferably an electromagnetic clutch  213  coupled to gearbox  212  and flexible driveshaft  202  which is operable between a disengaged position wherein the transmission of drive torque between drive motor  210  and drive pinion  208  is inhibited, and an engaged position wherein the transmission of drive torque between drive motor  210  and drive pinion  208  is permitted. Preferably, drive clutch  206  is normally maintained in the disengaged position which prevents drive pinion  208  from back-driving drive motor  210  when sliding door  36  is manually moved between the fully-open and closed positions. Configuration in this manner permits sliding door  36  to be opened and closed manually without substantially increasing the force required to propel the door as compared to a completely manual sliding door. Hall effect sensor  214  is operable for generating a position signal indicative of the position of drive motor  210  at a predetermined position. Hall effect sensor  214  is coupled to control module  54 , enabling control module  54  to receive the position signal and monitor the operation of drive motor  210 , including the speed by which it rotates. 
     As shown most particularly in FIG. 11, lower hinge member  168  includes a raised portion  240  which extends around drive pinion  208  and flexible driveshaft  202 . Raised portion  240  functions as a guard to prevent foreign objects from contacting spur gear teeth  230  of drive pinion  208  as it rotates, as well as providing drive pinion  208  and flexible driveshaft  202  with additional protection against impacts caused by persons or equipment entering or exiting vehicle  12  through side opening  16 , as well as providing structural strength to lower hinge member  168 . 
     With reference to FIGS. 15-23, power latching mechanism  126  is illustrated to include a latch mechanism  250 , a power drive assembly  252 , a bracket member  254 , an unlatch mechanism  256  and a child guard mechanism  258 . Latch mechanism  250  is shown to include a housing  260 , a latch ratchet  262 , a latch sector  264 , a pawl  266 , a dog member  268 , first, second and third spring means  270 ,  272  and  274  respectively, first and second pins  276  and  278 , respectively, a pawl switch  280 , a ratchet switch  282  and a lock switch  714 . 
     Housing  260  includes a container-like base portion  290 , a molded body portion  292  and a cover  294 . With particular reference to FIGS. 16 through 18, base portion  290  is shown to include a front surface  296 , a side surface  298 , a pair of pin apertures  300  sized to receive first and second pins  276  and  278 , a slotted aperture  302  formed into front and side surfaces  296  and  298  and a plurality of retaining tangs  304 . Body portion  292  includes a mid-wall  306  defining first and second cavities  308  and  310 , respectively, a striker receiver  312 , first and second pin apertures  314  and  316 , respectively, sized to receive first and second pins  276  and  278 , respectively, a contact tab aperture  318  and a pawl actuation aperture  320 . First cavity  308  includes a first boss  322 , a second boss  324  and first and second spring apertures  326  and  328 , respectively. Second boss  324  extends through midwall  306  into second cavity  310 . Cover  294  includes a drive aperture  330 , a pair of pin apertures  332  sized to receive first and second pins  276  and  278  and a plurality of tang apertures  334  sized to receive retaining tangs  304 . 
     As shown particularly in FIGS. 20-22, latch ratchet  262  is a disc-shaped fabrication which includes a slotted striker aperture  340 , a first boss aperture  342 , a pawl contact surface  344  having first, second and third pawl contact portions  346 ,  348  and  350 , respectively, a latch sector contact surface  352 , a spring tab  354  and first and second pawl apertures  356  and  358 , respectively. Latch ratchet or member  262  is coupled to body portion  292  in first cavity  308  such that first boss  322  extends through first boss aperture  342 . First spring means  270  is disposed within first spring aperture  326  and contacts spring tab  354  to thereby normally urge latch ratchet  262  clockwise (as shown in FIG. 20) into a fully unlatched position. First pawl contact portion  346  is configured to contact ratchet switch  282  when pawl  266  is engaged against either second or third pawl contact portions  348  and  350 . 
     Pawl  266  includes a second boss aperture  360 , a coupling aperture  362 , and first and second contact surfaces  364  and  366 , respectively. Pawl  266  is coupled to body portion  292  in first cavity  308  such that second boss  324  extends though second boss aperture  360 . Second spring means  272  is disposed within second spring aperture  328  and contacts pawl  266  along a side opposite first contact surface  364 . Second spring means  272  urges pawl  266  against pawl contact surface  344 , causing pawl  266  to rotate toward latch ratchet  262  when positioned proximate one of the first and second pawl apertures  356  and  358 . As first spring means  270  urges latch ratchet  262  in an opposite direction, contact between latch ratchet  262  and pawl  266  is maintained between second pawl contact portion  366  and second pawl contact portion  348  when pawl  266  is positioned in first pawl aperture  356 , thereby locking latch ratchet  262  in an ajar position. Similarly, contact between latch ratchet  262  and pawl  266  is maintained between third pawl contact portion  350  and second contact surface  366  when pawl  266  is positioned in second pawl aperture  358 , thereby locking latch ratchet  262  in a fully latched position. 
     Latch sector  264  includes a cylindrical body portion  370  having a pin aperture  372 , a contact tab  374 , a geared surface  376  having a plurality of gear teeth  378 , and a ratchet contact  380 . First pin  276  couples latch sector  264  to housing  260 . First pin  276  supports latch sector  264  for rotation about first pin  276  between a returned position and an extended position as shown in FIG.  16 . Third spring means  274  is coupled to latch sector  264  and body portion  292  and is operable for normally urging latch sector  264  to rotate about first pin  276  to the returned position. Geared surface  376  is proximate drive aperture  330  and allows latch ratchet  262  to be rotated about first pin  276  by a power drive assembly  252 . Contact tab  374  extends through contact tab aperture  318  such that rotation of latch sector  264  about first pin  276  in a first direction permits contact tab  374  to contact latch sector contact surface  352  and rotate latch ratchet  262  toward the fully latched position. 
     Dog member  268  includes an actuation arm  382 , a third boss aperture  384 , a pawl arm  386 , a sensor arm  388 , and a ratchet contact surface  390 . Actuation arm  382  includes a lever aperture  392 . Dog member  268  is coupled to body portion such that second boss  324  extends through third boss aperture  384 . Pawl arm  386  extends through pawl actuation aperture  320  and is received into coupling aperture  362  to couple dog member  268  and pawl  266  for rotation about second boss  324 . Dog member  268  is therefore operable for rotating pawl  266  outward from latch ratchet  262  to disengage pawl  266  from first and second pawl apertures  356  and  358  to permit latch ratchet  262  to return to the fully unlatched position. Actuation arm  382  cooperates with unlatch mechanism  256  to cause dog member  268  to rotate about second boss  324  to unlatch latch ratchet  262 . Latch sector  264  is also operable for rotating dog member  268  about second boss  324  to unlatch latch ratchet  262 . Rotation of latch sector  264  in a second direction opposite the first direction enables ratchet contact  280  to contact ratchet contact surface  390  to cause dog member  268  to rotate pawl  266  and unlatch latch ratchet  262 . Sensor arm  388  is configured to contact pawl switch  280  when pawl  266  is engaged in either of the first and second pawl apertures  356  and  358 . 
     First and second pins  276  and  278  extend through their respective pin apertures in base portion  290 , body portion  292  and cover  294 . Retaining tangs  304  extend through their respective tang apertures  334  and are preferably bent over to secure base portion  290  to cover portion  294 . Alternatively, retaining tangs  304  may also be welded cover portion  294 . 
     Slotted striker aperture  340  is sized to receive a striker  394  and is operable between a fully unlatched position as shown in FIG. 21, an ajar or partially latched position as shown in FIG. 22, and a fully latched position as shown in FIG.  23 . Slotted striker aperture  340  is configured in a manner which permits latch ratchet  262  to rotate toward the fully latched position when striker  394  contacts slotted striker aperture  340 . As such, latch ratchet  262  can be actuated to the fully latched position by manually placing sliding door  36  into the closed position. 
     Pawl switch  280  is coupled to control module  54  and is operative for producing a digital signal indicative of the position of latch ratchet  262 . In the particular embodiment illustrated, pawl switch  280  is shown to be a limit switch  396 . However, it will be understood that other switches, such as proximity switches, may also be used to generate a signal indicative of the position of latch ratchet  262 . When the signal produced by pawl switch  280  is high (i.e., open to ground), pawl  266  is engaged in one of the first and second pawl apertures  356  and  358 , indicating that latch ratchet  262  is in one of the ajar and fully latched positions. When the signal produced pawl switch  280  is low (i.e., closed to ground), latch ratchet  262  is in the fully unlatched position. 
     Ratchet switch  282  is also coupled to control module  54  and produces a digital signal indicative of the position of latch ratchet  262 . In the particular embodiment illustrated, ratchet switch  282  is similarly shown to be a limit switch  398 . Again, it will be understood that other switches, such as proximity switches, may also be used to generate a signal indicative of the position of latch ratchet  262 . When the signal produced by ratchet switch  282  is high, latch ratchet  262  is in the fully latched position. When the signal produced by ratchet switch  282  is low, latch ratchet  262  is in one of the ajar and fully unlatched positions. 
     Control module  54  utilizes the signals from ratchet switch  282  and pawl switch  280  to determine the position of sliding door  36  relative to striker  394 . For example, if both the signals produced by pawl and ratchet switches  280  and  282 , respectively, are low, power latching mechanism  126  is in the fully unlatched position. If the signal produced by pawl switch  280  is high and the signal produced by ratchet switch  282  is low, power latching mechanism  126  is in the ajar position. If both the signals produced by pawl and ratchet switches  280  and  282 , respectively, are high, power latching mechanism  126  is in the fully latched position. 
     With particular reference to FIGS. 15 and 24, power drive assembly  252  is shown to include a housing  410 , a cinch motor  412 , a gear train  414 , a cinch clutch  416  and a wiring harness  418 . Cinch motor  412  is operable in a first rotational direction and a second rotational direction. Cinch motor  412  includes a body portion  420  having a plurality of retaining slots  422 , first and second power terminals  424  and  426 , respectively, first and second body journals  428  and  430 , respectively, and an output shaft  432 . First and second body journals  428  and  430  extend from body portion  420  and are coaxial to both body portion  420  and output shaft  432 . Output shaft  432  includes a plurality of longitudinally splined teeth  434  at the end opposite body portion  420 . 
     Housing  410  includes a first housing portion  440 , a second housing portion  442  and a plurality of threaded fasteners  444  to couple first and second housing portions together. With additional reference to FIG. 25, first housing portion  440  is shown to include a wiring aperture  450 , motor support means  452 , first and second gear axles  454  and  456 , respectively, a cylindrical recess  458 , a bushing aperture  460 , a hollow cylindrical bushing  462 , a wire harness stop  464  and a plurality of retaining apertures  466 . Motor support means  452  includes first and second retaining tabs  468  and  470 , respectively, and first and second support tabs  472  and  474 , respectively. First and second retaining tabs  468  and  470  each extend inward from a sidewall  476  which bounds first housing portion  440  along its sides. Retaining tabs  468  and  470  engage retaining slots  422  and are operable for preventing body portion  420  from rotating relative to first housing portion  440 . First support tab  472  extends upward from the base  478  of first housing portion  440  and includes a slotted aperture  480  which is sized to receive first body journal  428 . Second support tab  474  extends upward from base  478  and is coupled to sidewall  476  in two locations. Second support tab  474  includes a slotted aperture  482  sized to receive second body journal  430 , a first vertical slot  484  sized to receive a portion of wiring harness  418  and first power terminal  424 , and a second vertical slot  486  sized to receive second power terminal  426 . First and second support tabs  472  and  474  cooperate to align the axis of output shaft  432  as well as the position of drive motor  210  in their proper orientations relative to first gear axle  454 . 
     With reference to FIG. 26, second housing portion  442  is shown to include a motor entrapment means  490 , first and second axle bores  492  and  494 , respectively, a cylindrical recess  496 , a bushing aperture  498 , a hollow cylindrical bushing  500  and a plurality of retention apertures  502 . First and second axle bores  492  and  494  are sized to receive first and second gear axles  454  and  456 , respectively. Motor entrapment means  490  includes first and second tabs  508  and  510  extending from the top surface  512  of second housing portion  442 . First and second tabs  508  and  510  are positioned along top surface  512  so as to be proximate first and second support tabs  472  and  474 , respectively when first and second housing portions  440  and  442  are coupled together. As such, first and second tabs  508  and  510  are operable for limiting the movement of first and second body journals  428  and  430 , respectively to thereby control the orientation of output shaft  432  relative to first gear axle  454 . 
     Referring back to FIG. 24, gear train  414  is shown to include a worm gear  520  and a plurality of reducing gears  522   a  and  522   b  which cooperate to drive an output pinion  524 . Worm gear  520  is conventional in construction and includes thread like teeth  526  and a central aperture (not shown). Worm gear  520  is pressed onto output shaft  432  and engages splined teeth  434  to prevent relative rotation between worm gear  520  and output shaft  432 . As such, worm gear  520  is coupled for rotation with output shaft  432 . 
     Reducing gear  522   a  includes an axle aperture  528 , a plurality of helical gear teeth  530  having a first pitch diameter and a plurality of spur gear teeth  532  having a second, smaller pitch diameter. First gear axle  454  extends through axle aperture  528  and helical gear teeth  530  meshingly engage thread-like teeth  526 . As such, rotation of worm gear  520  causes reducing gear  522 a to rotate about first gear axle  454 . 
     Reducing gear  522   b  includes an axle aperture  534 , a plurality of first spur gear teeth  536  having a first pitch diameter, and a plurality of second spur gear teeth  538  having a second, smaller pitch diameter. Second gear axle  456  extends through axle aperture  534  and first spur gear teeth  536  meshingly engage spur gear teeth  532 . As such, rotation of reducing gear  522   a  causes reducing gear  522   b  to rotate about second gear axle  456 . 
     Cinch clutch  416  is operable for interrupting the transfer of drive torque from cinch motor  412  to output pinion  524 . Preferably, cinch clutch  416  permits output pinion  524  to freely rotate about its axis when cinch clutch  416  is disengaged. Operation in this manner permits power latching mechanism  126  to be operated manually or automatically. 
     Cinch clutch  416  is preferably electronically controlled and includes an electromagnet  540 , a selectively engagable reducing gear  542  and a low friction element  543  disposed between electromagnet  540  and selectively engagable reducing gear  542 . Electromagnet  540  is generally cylindrical in shape and includes an inductive coil  540   a  and a casing  540   b.  Inductive coil  540   a  is shown to include a central aperture  544  and positive and negative power leads  546  and  548 , respectively. Electromagnet  540  and cinch motor  412  are coupled to wire harness  418  in a parallel manner such that activation of cinch motor  412  also activates electromagnet  540 . Wire harness stop  464  is operable for preventing gear teeth  538  from contacting wire harness  418  to ensure reliable operation of electromagnet  540 . 
     Selectively engagable gear mechanism  542  includes first and second members  550  and  552 , respectively. With additional reference to FIG. 27, first member  550  is shown to include a first gear member  560 , a second gear member  562 , a washer  564 , a spring means  566  and a retaining ring  568 . First gear member  560  is generally cylindrical in shape and includes a plurality of spur gear teeth  570  which meshingly engage second spur gear teeth  538 , a plurality of radial apertures  572 , a second member pocket  574  and a shoulder  576  having a central aperture  578  and a ring groove  580  sized to receive retaining ring  568 . Second gear member  562  includes a disc-shaped geared portion  582  and a plurality of cylindrical pins  584 . Geared portion  582  includes a plurality of radial splines  588  and an aperture  586  having a counter bore  592  of a first diameter and a through-hole  594  of a second, smaller diameter. Radial apertures  572  are each sized to receive a cylindrical pin  584  which are installed to geared portion  582  by press-fitting. Through-hole  594  is sized to receive shoulder  576 . Counter bore  592  is sized to provide both radial and axial clearance for washer  564 , spring means  566  and retaining ring  568 . Second gear member  562  is installed to first gear member  560  by engaging cylindrical pins  584  into their respective radial apertures  572  and engaging shoulder  576  into through-hole  594 . Spring means  566  is preferably a spring washer  596  which biases second gear member  562  upward into second member pocket  574 . Cylindrical pins  584  are operable for guiding second gear member  562  in an axial direction relative to first gear member  560  and also for ensuring the transmission of drive torque between first and second gear members  560  and  562 . 
     Second member  552  includes first and second shaft portions  600  and  602 , respectively, gear member  604  and output pinion  524 . First shaft portion  600  is sized to rotate within aperture  578  and bushing  462 . Second shaft portion  602  is sized to rotate within aperture  544  and bushing  500 . As such, second member  552  is supported for rotation within first and second housing portions  440  and  442 . Gear member  604  is fixed for rotation with first shaft portion  600  and includes a plurality of radial splines  608  that are similar to those of second gear member  562 . Second shaft portion  602  is coupled for rotation with gear member  604  and is supported for rotation within bushing  500 . Output pinion  524  is coupled for rotation with second shaft portion  602  and includes a plurality of spur gear teeth  610  having a pitch diameter smaller than that of spur gear teeth  570 . Gear teeth  610  extend through drive aperture  330  and meshingly engages gear teeth  378  such that latch sector  264  rotates when output pinion  524  rotates about its axis. 
     As spring means  566  normally biases second gear member  562  upward into first gear member  560 , radial splines  588  and  608  are not normally engaged. Consequently, rotation of first member  550  does not normally cause rotation of second member  552  and vice-versa. Therefore, the size of third spring means  274  may be reduced since returning latch sector  264  to the returned position does not “back drive” gear train  414 . 
     Operation of cinch motor  412  in either of the first and second rotational directions also causes the energization of electromagnet  540 . When electromagnet  540  is energized, a magnetic field (not shown) is created which draws second gear member  562  toward gear member  604  so that radial splines  588  and  608  meshingly engage. Once radial splines  588  and  608  have engaged, drive torque input to first gear member  560  from second reducing gear  522   b  is transmitted to gear member  604  causing second shaft portion  602  to rotate. Rotation of second shaft portion  602  in a first direction causes output pinion  524  to drive latch sector  264  about first pin  276  in a first direction. Contact between contact tab  374  and latch sector contact surface  352  which occurs as latch sector  264  is driven about first pin  276  in the first direction causes latch sector  264  to drive latch ratchet  262  in a direction toward the fully latched position. It should be apparent from the above description that as latch ratchet  262  is brought into the fully latched position, contact between latch ratchet  262  and striker  394  draws sliding door  36  into the fully latched position. Rotation of second shaft portion  602  in a second direction causes output pinion  524  to drive latch sector  264  about first pin  276  in a second direction. Contact between ratchet contact  380  and ratchet contact surface  390  which occurs as latch sector  264  is driven about first pin  276  in the second direction causes latch sector  264  to drive dog member  268  in a direction which causes pawl member  266  to disengage latch ratchet  262 . 
     Referring back to FIGS. 15 through 17, bracket member  254  may be fabricated as an individual component or may be combined with another component, such as the housing  260  of latch mechanism  250 . Bracket member  254  includes a unlatch mechanism stop  620 , first, second and third Bowden cable support apertures  622 ,  624  and  626 , respectively, first and second spring apertures  628  and  630 , respectively, first and second pin apertures  632  and  634 , respectively, and first and second child guard lever apertures  636  and  638 , respectively. 
     Unlatch mechanism  256  includes an interior unlatch lever  640 , an exterior unlatch lever  642 , a dog lever  644 , first and second pins  646   a  and  646   b,  a first spring means  648 , a latch lock mechanism  650  and second spring means (not shown). Exterior unlatch lever  642  includes a pin aperture (not shown), a slotted aperture  654 , a stop means  656 , a generally L-shaped slot  658  and cable retention means  660 . With additional reference to FIGS. 28 and 29, cable retention means  660  is formed in a container-like shape having a plurality of sidewalls  662  and an end wall  664 . A cable slot  666  extends though sidewalls  662   a  and  662   b  into a portion of end wall  664  and terminates in a seat aperture  668 . 
     Interior unlatch lever  640  includes a pin aperture  670 , a generally L-shaped slotted aperture  672 , a contact surface  674 , first and second Bowden cable retention means  676  and  678 , respectively, and a spring aperture  680 . First Bowden cable retention means  676  includes a base member  682  and a generally L-shaped leg member  684 . Base member  682  is fixed to interior unlatch lever  640 , thereby coupling first Bowden cable retention means  676  to interior unlatch lever  640 . Leg member  684  includes a base portion  686  and a leg portion  688 . Leg portion  688  spaces base portion  686  apart from base member  682  a predetermined first distance. A cable slot  690  extends through leg member  684  and into a portion of base member  682  where it terminates in a seat aperture  692 . 
     Second Bowden cable retention means  678  also includes a base member  694  and a leg member  696 . Base member  694  is fixed to interior unlatch lever  640 , thereby coupling second Bowden cable retention means  678  to interior unlatch lever  640 . Leg member  696  is spaced apart from interior unlatch lever  640  at a predetermined second distance. A cable slot (not shown) extends through base member  694  where it terminates in a seat aperture (not shown). 
     Dog lever  644  includes a pin aperture (not shown), a slotted aperture  700  and a dog actuation lever  702 . First pin  646 a is inserted through the pin apertures in dog lever  644 , interior and exterior unlatch levers  640  and  642 , and press-fit into aperture  632 , thereby coupling interior and exterior unlatch levers  640  and  642  and dog lever  644  to bracket member  254  as well as supporting these levers for rotation about first pin  646   a.  Dog lever  644  and actuation arm  382  are coupled together such that dog actuation lever  702  extends into lever aperture  392 . As such, dog lever  644  and actuation arm  382  are operable for actuating one another. 
     Latch lock mechanism  650  includes a link connecting arm  704 , a pin aperture  706 , a spring aperture (not shown), an unlatch lever arm  708  having an actuation slot  707 , and an unlatch lever pin  710 . Second pin  646   b  is inserted through pin aperture  706  and press-fit into pin aperture  634 , thereby coupling latch lock mechanism  650  to bracket member  254  was well as supporting the mechanism for rotation about second pin  646   b.  Unlatch lever pin  710  is coupled to unlatch lever arm  708  and extends through L-shaped slot  658 . Rotation of latch lock mechanism  650  about second pin  646   b  is operable for placing unlatch lever pin  710  in an engaged mode or a disengaged mode. Unlatch lever pin  710  is positioned in the engaged mode when it lies within the narrow slotted tip portion  712  of L-shaped slot  658 . Unlatch lever pin  710  is positioned in the disengaged mode when it does not lie within the narrow slotted tip portion  712  of L-shaped slot  658 . 
     A lock switch  714  is coupled to control module  54  and produces a digital signal indicative of the status of latch lock mechanism  650 . When latch lock mechanism  650  is placed in the engaged position, lock switch  714  produces a high signal (i.e., open to ground) which causes control module  54  to inhibit the operation of sliding door  36  in an automatic mode unless the position of latch lock mechanism  650  is first changed to the disengaged position. 
     First Bowden cable  150  couples exterior handle  148  to exterior unlatch lever  642 . First Bowden cable  150  includes a hollow cable sheath  716 , a resilient retaining grommet  718  coupled to cable sheath  716 , a braided wire cable  720  disposed within cable sheath  716  and a first Bowden cable retainer  722 . As shown in FIG. 28, first Bowden cable retainer  722  is an aluminum sphere  724  which is staked or otherwise secured to the end of braided wire cable  720 . The diameter of sphere  724  is sized to fit between sidewalls  662  with a predetermined amount of clearance. The predetermined amount of clearance prevents first Bowden cable retainer  722  from binding one or more sidewalls  662  as exterior unlatch lever  642  is operated. However, the amount of predetermined clearance is sufficiently small to ensure that if an assembly or service technician attempted to place a Bowden cable retainer from another cable into first Bowden cable retainer  722 , the Bowden cable retainer would either be too large to fit within sidewalls  662  or would fit too loosely within sidewalls  662  so as to make such assembly errors readily apparent to the technician. Similarly, the predetermined first distance between base member  682  and leg member  684  is selected so as to render the misassembly of first Bowden cable retainer  722  into first Bowden cable retainer  676  apparent to the technician. First Bowden cable  150  is threaded into cable slot  666  and sphere  724  is positioned between sidewalls  662 . Retaining grommet  718  is inserted into first support aperture  622  to secure first Bowden cable  150  to bracket member  254 . Retaining grommet  718  is sized to fit first support aperture  622  and is either too large or small to fit second and third support apertures  624  and  626  properly. As such, the misassembly of first Bowden cable  150  to second or third support apertures  624  or  626  will be immediately apparent to assembly and service technicians. 
     A second Bowden cable  154  couples interior handle  152  to interior unlatch lever  640 . Second Bowden cable  154  similarly includes a hollow cable sheath  726 , a resilient retaining grommet  728  coupled to cable sheath  726 , a braided wire cable  730  disposed within cable sheath  726  and a second Bowden cable retainer  732 . Second Bowden cable retainer  732  is an aluminum sphere  734  which is staked or otherwise secured to the end of braided wire cable  730 . The diameter of sphere  734  is sized to match the distance between base portion  686  and base member  682  with a predetermined amount of clearance similar to that discussed above for first Bowden cable retainer  722 . The diameter of sphere  734 , however, is sufficiently different from that of sphere  722  so as to prevent its insertion into cable retention means  660 . Second Bowden cable  154  is threaded into cable slot  690  and sphere  734  is positioned between base portion  686  and base member  682 . Retaining grommet  728  is sized to fit second support aperture  624  and is either too large or small to fit first and third support apertures  622  and  626  properly. As such, the misassembly of second Bowden cable  154  to first or third support apertures  622  or  626  will be immediately apparent to assembly and service technicians. 
     A third Bowden cable  736  couples hold-open latch  128  to interior unlatch lever  640 . Third Bowden cable  736  again similarly includes a hollow cable sheath  738 , a resilient retaining grommet  740  coupled to cable sheath  738 , a braided wire cable  742  disposed within cable sheath  738  and a third Bowden cable retainer  740 . Third Bowden cable retainer  740  is fabricated from aluminum and includes a sphere portion  740   a  and a plate portion  740   b  which is fixedly secured to sphere portion  740   a.  Third Bowden cable retainer  740  is staked or otherwise secured to the end of braided wire cable  742 . The unique configuration of third Bowden cable retainer  740  prevents or renders apparent the misassembly of the Bowden cable retainer  740  to either cable retention means  660  or first Bowden cable retention means  676 . Third Bowden cable  736  is secured to second Bowden cable retention means  678  in a manner similar to that described above for second Bowden cable  154 . Retaining grommet  740  is inserted into third support aperture  626  to secure third Bowden cable  736  to bracket member  254 . Retaining grommet  740  is sized to fit third support aperture  626  and is either too large or small to fit first and second support apertures  622  and  624  properly. As such, the misassembly of third Bowden cable  736  to first or second support apertures  622  or  624  will be immediately apparent to assembly and service technicians. 
     Referring briefly to FIG. 30, a cable retention means and a Bowden cable retainer according to an alternate embodiment are shown. As shown, Bowden cable retainer  750  is generally cylindrical in shape, formed from a material such as aluminum and coupled to an end of braided wire cable  752  in a conventional manner. Cable retention means  754  is generally shaped in the form of a hollow cylinder and includes an T-shaped cable slot  756  with a first portion  758  extending parallel to the axis of cable retention means  754  and a second portion  760  which extends around a portion of the perimeter of cable retention means  754 . Bowden cable retainer  750  is sized in a manner which includes a predetermined amount of clearance as described above. Wire cable  752  is threaded into cable slot  756  and Bowden cable retainer  750  is inserted into the hollow interior of cable retention means  754 . When wire cable  752  reaches second portion  760 , Bowden cable retainer  750  is rotated within cable retention means  754  to guard against the withdrawal of Bowden cable retainer  750 . 
     In one application, the aluminum sphere  724  of first Bowden cable retainer  722  has a diameter of approximately 6 mm, the aluminum sphere  734  of second Bowden cable retainer  732  has a diameter of approximately 8 mm and the distance between sidewalls  662  is approximately 6.5 mm. Accordingly, as second Bowden cable retainer  732  will not fit into cable retention means  660 , any assembly errors would be rendered immediately apparent. In further illustration of the error-proofing method of the present invention, the diameter of first support aperture  622  is approximately 12 mm and the diameter, the diameter of first retaining grommet  718  is approximately 11.5 mm, the diameter of second support aperture  624  is approximately 8.5 mm and the diameter of second retaining grommet  728  is approximately 8 mm. Accordingly, as the diameter of first retaining grommet  718  is substantially larger than second support aperture  624  to prevent its insertion therein, any assembly errors would be rendered immediately apparent. 
     From the foregoing discussion, it should be readily apparent to those skilled in the art that the error-proofing of an assembly having multiple wire cables can be accomplished by utilizing a series of cables having Bowden cable retainers of the same shape which are sized differently and/or by utilizing cables with Bowden cable retainers of different shapes. 
     With additional reference to FIG. 17B, actuation of exterior handle  148  creates a force that is transmitted through first Bowden cable  150  and acts against end wall  664  to cause exterior unlatch lever  642  to rotate about first pin  646   a.  If unlatch lever pin  710  is in the engaged mode, unlatch lever pin will contact unlatch lever arm  708 , as well as exterior unlatch lever  642  along the narrow portion  712  of L-shaped slot  658 , causing unlatch lever pin  710  to rotate about second pin  646   b  in actuation slot  707 . As unlatch lever pin  710  extends through exterior unlatch lever  642 , rotation of exterior unlatch lever  642  about first pin  646   a  causes unlatch lever pin  710  rotate outward from second pin  646   b  and rotate dog lever  644  about first pin  646   a.  If dog lever  644  is sufficiently rotated about first pin  646   a,  actuation lever  702  contacts actuation arm  382  which in turn causes dog member  268  to rotate pawl  266  away from latch ratchet  262  to permit first spring means  270  to rotate latch ratchet  262  to the fully open position. If, however, unlatch lever pin  710  is in the disengaged mode, rotation of exterior unlatch lever  642  will not cause unlatch lever pin  710  to contact dog lever  644 , and as such, actuation lever will not contact actuation arm  382  to cause dog member  268  to rotate pawl  266  and release latch ratchet  262 . 
     With reference to FIG. 17C, actuation of interior handle  152  (i.e., release button  152   a ) creates a force that is transmitted through second Bowden cable  154  and acts against base member  682  to cause interior unlatch lever  640  to rotate about first pin  646   a.  Actuation of interior handle  152  also creates a force which is transmitted through third Bowden cable  736 , which in turn causes hold-open latch  128  to pivot about its connection to door assembly  138  and release first guide track  38 . Child guard mechanism  258  selectively couples interior unlatch lever  640  to exterior unlatch lever  642 . 
     Child guard mechanism  258  includes a first link  780  which is pivotably coupled to bracket member  254  at first child guard lever aperture  636 , a second link  782  which is pivotably coupled to bracket member at second child guard lever aperture  638 , and a third link  784 . First link  780  includes a selector arm  786  and an actuation arm  788 . Selector arm  786  is operable between an engaged position which permits latch ratchet  262  to be unlatched only by manual operation of exterior handle  148  and a disengaged position which permits latch ratchet  262  to be unlatched by automatic operation or by manual operation of the exterior or interior handles  148  and  152 . Second link  782  is coupled to first link  780  such that movement of first link  780  between the engaged and disengaged positions causes second link  782  to rotate about second child guard lever aperture  638 . Third link  784  is pivotably coupled to second link  782  and includes an actuation pin  790 . Actuation pin  790  extends through slotted aperture  654  and L-shaped slot  672 . 
     Positioning of child guard mechanism  258  into the disengaged position places actuation pin  790  in a portion of L-shaped slot  672  proximate its tip  792 . Therefore, when child guard mechanism  258  is disengaged and interior unlatch lever  640  is rotated about first pin  646   a,  actuation pin  790  is brought into contact with the side of L-shaped slot  672 , causing exterior unlatch lever  642  to rotate about first pin  646   a  with interior unlatch lever  640 . Consequently, the actuation of interior handle  152  when child guard mechanism  258  is disengaged permits interior unlatch lever  640  to rotate exterior unlatch lever  642  and unlatch power latching mechanism  126  as described above. 
     Positioning of child guard mechanism  258  into the engaged position places actuation pin  790  in a portion of L-shaped slot  672  proximate its base  794 . Therefore, when child guard mechanism  258  is engaged and interior unlatch lever  640  is rotated about first pin  646   a,  actuation pin  790  does not contact the side of slotted aperture  672  and the position of exterior unlatch lever  642  is not affected. Consequently, the actuation of interior handle  152  when child guard mechanism  258  is engaged does not permits interior unlatch lever  640  to rotate exterior unlatch lever  642  and unlatch power latching mechanism  126 . 
     Child guard mechanism  258  permits exterior handle  148  to actuate hold-open latch  128  to release first guide track  38 . Specifically, the rotating motion of exterior unlatch lever  642  in a direction tending to unlatch power latching mechanism  126  is transmitted to interior unlatch lever  640  to cause it to similarly rotate about first pin  646   a.    
     From the foregoing discussion of latch mechanism  250  and power drive assembly  252 , above, it should be readily apparent to those skilled in the art that power latching mechanism  126  may be configured in a manner to permit its integration into other vehicle closure systems, including tailgates and other passenger doors which are pivotably coupled to a vehicle body, as wells as trunk lids and hoods. With reference to FIGS. 1,  3 A and  3 B, a power latching mechanism according to an alternate embodiment which is tailored for use in tailgate  64  is generally indicated by reference numeral  126 ′. Power latching mechanism  126 ′ does not include a bracket member or a child guard mechanism. Power latching mechanism  126 ′ is otherwise generally similar to power latching mechanism  126  except that unlatch mechanism  256 ′ is highly simplified and consists of a single lever  800  pivotably coupled to housing  260 ′. Wire harness  67   d  extends into a hole  801  in tailgate panel  65  which is sealed by sealing grommet  67   e.  Wire harness  67   d  is coupled to body control module  52 . 
     Power latching mechanism  126 ′ is fixedly coupled to tailgate panel  65 . Lever  800  is mechanically coupled through a link member  802  to key switch  66 . Rotation of key switch  66  in a first direction causes link member  802  to rotate lever  800  which in turn causes dog member  268  to rotate about second pin  278  and release pawl  266  to unlatch power latching mechanism  126 ′. Power latching mechanism  126 ′ is electrically coupled to body control module  52 . Body control module  52  is operable for monitoring the state of the pawl and ratchet switches  280  and  284  and determining the latched state of power latching mechanism  126 ′. Body control module  52  is also operable for monitoring-the output signals generated by tailgate handle switch  67   c,  an interior switch  134  or a remote keyless-entry control device  962 . Upon receiving an output signal from tailgate handle switch  67   c,  interior switch  134  or remote keyless-entry control device  962  indicative of a command to cause power latching mechanism  126 ′ to unlatch, body control module  52  is first determines whether latch ratchet  262  is in the fully unlatched position. If latch ratchet  262  is not in the fully unlatched position, body control module  52  is operable controlling cinch motor  412  to operate and drive latch sector  264  in the second direction to cause ratchet contact  280  to contact ratchet contact surface  390  and rotate pawl  266  to release latch ratchet  262  as described above. 
     Consequently, tailgate may be operated without conventional interior and exterior handles which mechanically operate the latching mechanism. This construction is advantageous in that it permits any holes in the exterior surface  804  of tailgate panel  65  to be sealed against entry by dirt and water under conditions in which vehicle  12  would normally be operated. This construction is also advantageous due to the ability to reduce the number of parts comprising the tailgate, as well as the ability to eliminate issues relating to the design and adjustment of conventional mechanical linkages associated with conventional interior and exterior handles for mechanically actuating the latch mechanism. 
     From the foregoing, it should be readily apparent to those skilled in the art that other power latch mechanism may be employed to eliminate conventional handles for mechanically operating the latch. Consequently, the scope of this aspect of the present invention is not limited to a power latching mechanism having cinching capabilities, but extends to any latching mechanism which may be electrically or electromechanically operated in an unlatching manner. It should also be readily apparent to those skilled in the art that this aspect of the present invention has applicability to other types of door handles and doors and as such, it not limited to lightbar assemblies or tailgates. 
     It should also be readily apparent to those skilled in the art that the power latch mechanism of the present invention may be coupled to the opposite side of the sliding door to engage a striker coupled to the second body pillar (i.e., second body pillar  26 ). This configuration is especially advantageous in that the hold-open latch may be designed in a manner to engage the striker when the sliding door is in the fully open position. 
     A power door drive mechanism according to an alternate embodiment of the present invention is generally indicated by reference numeral  124 ′ in FIGS. 31 through 33. Power door drive mechanism  124 ′ includes power unit  200 , a drive unit  204 ′, a drive clutch  206 ′, and a drive pinion  208 ′. Power unit  200  includes drive motor  210 , gearbox  212  and driveshaft  202 . 
     Drive pinion axle  900  extends through an aperture  902  in drive pinion  208 ′ and couples drive pinion  208 ′ to lower hinge member  168 ′. Drive pinion axle  900  also supports drive pinion  208 ′ for rotation about the longitudinal axis of drive pinion axle  900 . Drive pinion  208 ′ includes a plurality of drive pinion teeth  230 ′ which meshingly engage rack teeth  92 . 
     Drive unit  204 ′ includes a worm gear  904 , a reducing gear  906 , an idler gear  908 , first and second axles  910  and  912  and a mounting assembly  914 . Mounting assembly  914  supports worm gear  904  for rotation about its longitudinal axis. Driveshaft  202  is coupled to worm gear  904  and drives it about its longitudinal axis. Reducing gear  906  includes an axle aperture  916 , a set of first gear teeth  918  which meshingly engage the teeth  920  worm gear  904 , and a set of second gear teeth  922 . First axle  910  is disposed through lower hinge member  168 ′, mounting assembly  914  and axle aperture  916  and thereby supports reducing gear  906  for rotation about the axis of first axle  910 . First axle  910  also supports drive unit  204 ′ for rotation about the axis of first axle  910 . Idler gear  908  includes an axle aperture  924  and a set of gear teeth  926  which meshingly engage second gear teeth  922  and the teeth  230 ′ of drive pinion  208 ′. Second axle  912  is disposed through mounting assembly  914  and axle aperture  924  and thereby supports idler gear  908  for rotation about the axis of second axle  912 . 
     Drive clutch  206 ′ includes first and second hinge members  930  and  932 , respectively, which are pivotably connected by a pivot pin  934 . First hinge member  930  is generally L-shaped and includes a cam  936  at the intersection of base portion  938  and leg portion  940 . A pivot pin  942  couples first hinge member  930  to the portion of mounting assembly  914  proximate idler gear  908 . Second hinge member  932  includes a cam follower  944 , a link portion  946 , and a pivot pin  948 . Cam follower  944  is coupled to link portion  946  includes a cam follower edge  950  which abuts leg portion  940  when drive clutch  206 ′ is not actuated. Link portion  946  is pivotably coupled to first hinge member  930  by pivot pin  934 . First and second hinge members  930  and  932  are coupled to unlatch mechanism  256 ′ by first and second links  954  and  956 , respectively. First and second links  954  and  956  are preferably Bowden cables having a braided wire cable material. 
     When one or both of the exterior and interior handles  148  and  152  are placed in their extended positions, first link  780  creates a force as shown by direction arrow A in FIG. 33 which causes first hinge member  930  to rotate about pin  934 . In response thereto, cam  936  is caused to act against cam follower  944  and rotate mounting assembly  914  about first axle  910  into a disengaged position wherein idler gear  908  is disengaged from drive pinion  208 ′ to permit sliding door  36 ′ to be operated manually. Depending upon the configuration of cam  936  and cam follower  944 , drive clutch  206 ′ may be locked into the disengaged position by the actuation of either one of the exterior or interior handles  148  and  1   52 . 
     Second link member  932  is coupled to a linear actuator  960  which, when actuated upon the occurrence of one or more predetermined conditions, creates a force as shown by direction arrow B in FIG. 33 which causes second link member  932  to rotate about pin  910  such that cam follower edge  950  abuts leg portion  940  and idler gear  908  engages drive pinion  208 ′. 
     Referring back to FIGS. 4 and 10, control module  54  is operable for selectively controlling the operation of sliding door  36 . Control module  54  is coupled to body control module  52  as well as various other electronic control devices throughout vehicle  12 , such as automatic transmission controller  50  and engine controller  48 . As a result, control module  54  receives data on numerous vehicle dynamics, including vehicle speed, ignition status, presently engaged gear ratio and requests to open sliding door  36  generated from one of the interior switches  134  or a remote keyless-entry control device  962 . Control module  54  is also coupled to drive motor  210 , drive clutch  206 , hall effect sensor  214 , pawl switch  280 , ratchet switch  282 , hold open switch  964 , lock switch  714 , cinch clutch  416 , cinch motor  412 , handle switch  146 , and a child guard switch  966 . 
     Control module  54  controls both the actuation of drive motor  210  and the direction with which it rotates. Operation of drive motor  210  in a first direction causes drive pinion  208  to be rotated in a direction which tends to push door panel assembly  138  into the open position. Conversely, operation of drive motor  210  in a second direction causes drive pinion  208  to be rotated in a direction which tends to push door panel assembly  138  into the closed position. 
     Control module  54  receives signals from various sensors located throughout vehicle  12 , determines the operational state of vehicle  12 , determines the appropriate actions that should be made with respect to sliding door  36  and initiates any necessary command signals to initiate such actions. Accordingly, upon receipt of a command to cycle sliding door  36  from one of the interior switches  134  or remote keyless-entry control device  962 , control module  54  determines the state of the sliding door (e.g. fully closed) and causes power door drive mechanism  124  and power latching mechanism  126  to operate according to a predetermined control strategy. 
     With reference to FIGS. 10 and 34, door assembly  136  includes trim panel assembly  140  and a stamped metal or molded plastic door panel assembly  138  that includes an exterior panel  1000  and an interior panel  1002 . Interior panel  1002  is fixedly coupled to exterior panel  1000  and includes a recessed cavity  1004  having a first portion  1006  adapted for housing control module  54  and a second portion  1008  adapted for housing a portion of power door drive mechanism  124 . In the particular embodiment illustrated, second portion  1008  includes a power unit cut-out  1012 , adapted to house drive motor  210  and gearbox  212 , and a driveshaft pocket  1014 , adapted to house a portion of flexible driveshaft  202 . Trim panel assembly  140  covers recessed cavity  1004  to conceal drive motor  210 , gearbox  212  and control module  54  from the view of the passengers, as well as to dampen any noise and vibration produced during the operation of sliding door  36 . Accordingly, trim panel assembly  140  may include an insulating material disposed between control module  54 , drive motor  210  and/or gearbox  212  and the interior of vehicle  12 . 
     The configuration shown is particularly advantageous due to its ability to be used across a wide range of vehicle trim levels. For example, should a completely manual sliding door be desired, the vehicle manufacturer need only omit power door drive mechanism  124  and control module  54 , substitute a completely mechanical version of the latching mechanism for power latching mechanism  126  and substitute a less complex wiring harness for wiring harness  190 . Preferably, the completely mechanical version of the latching mechanism is identical to power latching mechanism  126  except that any components or assemblies associated with the power latching and unlatching (e.g., power drive assembly  252 , latch sector  264 ) have been omitted or substituted with other components, such as spacers, to provide substantial similarity between the latch mechanisms in their installation and operation. 
     Similarly, should a manual sliding door with power locks be desired, the vehicle manufacturer need only omit power door drive mechanism  124  and control module  54 , substitute an electronically-actuated latching mechanism for power latching mechanism  126  and substitute a less complex wiring harness for wiring harness  190 . While the electronically-actuated latching mechanism may be the same component as the power latching mechanism  126 , it preferably substitutes a less-complex mechanism than power drive assembly  252  for actuating dog member  268  to permit latch ratchet  262  to return to the fully unlatched position. Configuration in this manner permits the cost of the latching mechanism to be minimized while maintaining substantial similarity between the latch mechanisms in their installation and operation. 
     It will be understood, however, that the cavity for drive motor  210 , gearbox  212  and/or control module  54  could alternatively be formed between exterior panel  1000  and interior panel  1002  (i.e., the cavity may be formed in door panel assembly  138 ). Accordingly, the particular embodiment illustrated is not intended to be limiting in any manner. 
     Referring to FIG. 35, the methodology for controlling sliding door  36  is shown in schematic flow-diagram form. The methodology is entered at bubble  2000  and progresses to decision block  2004  where control module  54  determines whether body control module  52  has issued a command signal (C 55  command) to open or close the sliding door  36 . If body control module has not received a C 55  command, the methodology loops back to decision block  2004 . If body control module  52  has received a C 55  command, the methodology proceeds to decision block  2008 . 
     In decision block  2008 , control module  54  evaluates data received from automatic transmission controller  50  to determine if vehicle is in a gear ratio corresponding to park or neutral. If vehicle is not in a gear ratio corresponding to park or neutral, the methodology returns to decision block  2004 . If vehicle is in a gear ratio corresponding to park or neutral, the methodology proceeds to decision block  2012  where control module  54  evaluates data received from engine controller  48  to determine if the speed of vehicle  12  is above a predetermined maximum speed. 
     If the speed of vehicle  12  is above the predetermined maximum speed in decision block  2012 , the methodology loops back to decision block  2004 . If the speed of vehicle  12  is not above the predetermined maximum speed, the methodology proceeds to decision block  2016  where the status of paw switch  280  is evaluated. If pawl switch  280  is in an open (i.e., open circuit to ground), latch ratchet  262  has been placed in one of the fully latched and partially latched positions. The methodology proceeds to decision block  2020  where the methodology determines if ratchet switch is open. If ratchet switch  282  is not open, the methodology proceeds to decision block  2024  where the methodology determines if a new C 55  command has been generated by body control module  52 . If a new C 55  command has not been generated, the methodology loops back to decision block  2004 . If a new C 55  command has been generated, the methodology proceeds to decision block  2028  where the methodology determines if sliding door  36  is being operated in an opening or a closing cycle. 
     If sliding door is not being operated in an opening or closing cycle, the methodology proceeds to bubble  2032  where the methodology proceeds along branch  2   c.  Referring now to FIG. 36, the methodology then proceeds from bubble  2032  to decision block  2036  where the status of ratchet switch  282  is evaluated. If ratchet switch  282  is open, the methodology proceeds to decision block  2040  where the status of pawl switch  280  is evaluated. If pawl switch  280  is open sliding door  36  is fully closed, and the methodology proceeds to bubble  2044  which, referring briefly to FIG. 35, causes the methodology to loop back to decision block  2004 . Returning to decision block  2040  in FIG. 36, if pawl switch  280  is not open, the methodology proceeds to block  2048  where cinch motor  412  is turned on in a closing direction, cinch clutch  416  is turned on and the cinch latch timer (CLT) is started. Referring back to decision block  2036 , if ratchet switch  282  is not open, the methodology proceeds to block  2048 . 
     The methodology proceeds to decision block  2052  where the status of ratchet switch  282  is evaluated. If ratchet switch  282  is not open, the methodology proceeds to decision block  2056 . In decision block  2056 , the methodology determines if the value of the CLT has exceeded a predetermined maximum time (T 2 ). In the particular example shown, T 2  is four seconds. If the value in the CLT has not exceeded T 2 , the methodology loops back to decision block  2052 . If the value of the CLT has exceeded T 2 , the methodology proceeds to block  2060  where cinch motor  412  and cinch clutch  416  are turned off. The methodology proceeds to block  2064  where a diagnostic troubleshooting code (DTC) is stored in the memory of control module  54 . The particular DTC stored aids technicians in evaluating failures in the power sliding door system  10  and also causes control module  54  to disable the automatic operation of sliding door  36 . 
     Referring back to decision block  2052 , if ratchet switch  282  is open, the methodology proceeds to decision block  2068  where the status of pawl switch  280  is evaluated. If pawl switch  280  is not open, the methodology proceeds to decision block  2072  where the methodology determines if the value in the CLT has exceeded T 2 . If the value in the CLT has not exceeded T 2 , the methodology loops back to decision block  2068 . If the value of the CLT has exceeded T 2 , the methodology proceeds to block  2060  and progresses as described above. 
     Returning to decision block  2068 , if pawl switch  280  is open, the methodology proceeds to block  2076  where the CLT is cleared. The methodology then proceeds to block  2080  where cinch motor  412  and cinch clutch  416  are turned off. The methodology then proceeds to bubble  2044  and progresses as described above. 
     Referring back to decision block  2028  in FIG. 35, if sliding door  36  is operating in an opening or a closing cycle, the methodology proceeds to decision block  2084  where the methodology determines if sliding door  36  is operating in an opening cycle. The methodology is able to determine the direction of operation through the use of the hold open switch  964 , the pawl and ratchet switches  280  and  284 , and through the use of a register which records whether the last cycle was an opening cycle or a closing cycle. For example, if the register indicated that the last cycle had been a closing cycle, the methodology will generally operate in an opening cycle the next time the power sliding door system  10 . An exception to this general rule of operation is where the hold open switch  964  had indicated that sliding door  36  was already in the fully open position. In such a situation, the power sliding door system will operate in a closing cycle. 
     Similarly, if the register indicates that the last cycle was an opening cycle, the methodology will generally operate in a closing cycle the next time the power sliding door system  10  is actuated. An exception to this general rule of operation is where the pawl and ratchet switches  280  and  284  indicate that sliding door  36  is already in the fully latched position. In such a situation, the power sliding door system will operate in an opening cycle. If sliding door  36  is operating in an opening cycle, the methodology loops back to decision block  2004 . If sliding door  36  is not operating in an opening cycle in decision block  2084 , the methodology proceeds to block  2088  and turns cinch motor  412  on in a releasing direction (i.e., such that latch sector  264  is operated in the second direction), cinch clutch  416  is turned on, and the cinch latch release timer (CLRT) is started. 
     The methodology then proceeds to decision block  2092  where the status of pawl switch  280  is evaluated. If pawl switch  280  is open, the methodology proceeds to decision block  2096  where the methodology determines if the value in the CLRT has exceeded a predetermined maximum time (T 2 ). If the value in the CLRT has not exceeded T 2 , the methodology loops back to decision block  2092 . If the value of the CLRT has exceeded T 2 , the methodology proceeds to block  2100  where cinch motor  412  and cinch clutch  416  are turned off. The methodology proceeds to block  2104  where a DTC is stored in control module  54  which prevents further operation of sliding door  36  in an automatic mode. 
     Returning to decision block  2092 , if pawl switch  280  is not open, the methodology proceeds to decision block  2108  where ratchet switch  282  is evaluated. If ratchet switch  282  is open, the methodology proceeds to decision block  2112  where the value in CLRT is evaluated. If the value in CLRT has exceeded T 2 , the methodology proceeds to block  2100 . If the value in CLRT has not exceeded T 2 , the methodology loops back to decision block  2108 . 
     Referring back to decision block  2108 , it ratchet switch  282  is not open, the methodology proceeds to block  2116  where drive clutch  206  is turned on and a Hall effect counter (HEC) is set to 0. The methodology proceeds to block  2120  where drive motor  210  is turned on and the power sliding door interrupt (PSDI) subroutine is started. The PSDI subroutine is discussed in detail below. The methodology proceeds to decision block  2124 . 
     In block  2124 , the methodology evaluates the speed of drive motor  210  utilizing the signal produced by Hall effect sensor  214 . If the speed of drive motor  210  is not greater than a predetermined speed (MSPD), the methodology proceeds to block  2128  where a DTC is stored in control module  54  which aids in the trouble shooting of power sliding door system  10 , but which does not disable the operation of sliding door  36  in a fully automatic mode. The methodology then proceeds to bubble  2132  where the methodology proceeds along branch  3   b.    
     Referring to FIG. 36, the methodology progresses from bubble  2132  to block  2136  where the present direction of drive motor  210  is reversed. The methodology proceeds to block  2140  where the logic for the HEC is adjusted to alter the value in the HEC in accordance with the new direction in which sliding door  36  is being moved. The methodology then proceeds to block  2144  where the C 55  command is cleared and the obstacle detection subroutine is started. The obstacle detection subroutine utilizes information from Hall effect sensor  214  to determine whether sliding door  36  has contacted an obstacle. The methodology proceeds to decision block  2148  where the value in the HEC is evaluated. 
     If the value in the HEC is greater than a first predetermined counter value (C 1 ), such as 560 counts, the methodology proceeds to block  2152  where the speed of drive motor  210  is decelerated to a predetermined motor speed. The methodology then proceeds to decision block  2156  where the methodology determines if sliding door  36  has contacted an obstacle. The methodology concludes that sliding door  36  had detected an obstacle, for example, if the value in the HEC is greater than a predetermined maximum counter value indicating that drive clutch  206  has experienced excessive slippage due to contact between sliding door  36  and an obstacle. 
     If sliding door  36  has not contacted an obstacle, the methodology proceeds to decision block  2160  where the status of pawl switch  280  is evaluated. If pawl switch is open, the methodology proceeds to block  2164  where drive motor  210  is turned off and the PSDI subroutine is terminated. The methodology proceeds to block  2168  where drive clutch  206  is turned off. The methodology then proceeds to decision block  2036  and continues in the manner described above. 
     Returning to decision block  2160 , if pawl switch  280  is not open, the methodology proceeds to decision block  2172  where the value in the HEC is evaluated. If the value in the HEC is not greater than a second predetermined counter value (C 2 ), the methodology proceeds to decision block  2176  where the C 55  command is evaluated. If a new C 55  command has not been issued, the methodology loops back to decision block  2156 . If a new C 55  command has been issued, the methodology proceeds to bubble  2180  and proceeds along branch  2   b.    
     Returning briefly to decision block  21   72 , if the value in HEC is greater than C 2 , the methodology proceeds to block  2184  where a DTC is stored in control module  54  which aids in the trouble shooting of power sliding door system  10 , but which does not disable the operation of sliding door  36  in a fully automatic mode. The methodology then proceeds to bubble  2180  and proceeds along branch  2   b.    
     Returning briefly to decision block  2156 , if an obstacle has been detected, the methodology proceeds to bubble  2180  and proceeds along branch  2   b.    
     Returning to decision block  2148 , if the value in HEC does not exceed Cl, the methodology proceeds to decision block where the C 55  command is evaluated. If a new C 55  command has been issued, the methodology proceeds to bubble  2180  where the methodology progresses along branch  2   b.  If a new C 55  command has not been issued, the methodology proceeds to decision block  2192  where the methodology determines if sliding door  36  has contacted an obstacle. If sliding door  36  has contacted an obstacle, the methodology proceeds to bubble  2180  and progresses along branch  2 b. If the methodology has not detected an obstacle, the methodology loops back to decision block  2148 . 
     Referring back to FIG. 35, the methodology proceeds from bubble  2180  to block  2196  where the present direction of drive motor  210  is reversed. The methodology proceeds to block  2200  where the logic for the HEC is adjusted to alter the value in the HEC in accordance with the new direction in which sliding door  36  is being moved. The methodology then proceeds to block  2204  where the C 55  command is cleared and the obstacle detection subroutine is started. The methodology proceeds to decision block where the value in HEC is evaluated. If the value in HEC is not greater than a third predetermined counter value (C 3 ), the methodology proceeds to decision block  2212  where the C 55  command is evaluated. 
     If a new C 55  command has been issued in decision block  2212 , the methodology proceeds to bubble  2132  and proceeds along branch  3   b  as described above. If a new C 55  command has not been issued in decision block  2212 , the methodology proceeds to decision block  2216  where the methodology determines if an obstacle has been detected. If an obstacle has been detected, the methodology proceeds to bubble  2132  and proceeds along branch  3 b as described above. If an obstacle has not been detected, the methodology loops back to decision block  2208 . 
     In decision block  2208 , if the value in the HEC is greater than C 3 , the methodology proceeds to block  2220  where drive motor  210  is decelerated to a predetermined speed. The methodology then proceeds to decision block  2224  where the value in the HEC is evaluated. If the value in the HEC is greater than C 2 , the methodology proceeds to block  2228  where a DTC is stored in control module  54  which aids in the trouble shooting of power sliding door system  10 , but which does not disable the operation of sliding door  36  in a fully automatic mode. The methodology proceeds to block  2232  where the value in the HEC is stored to the memory of control module  54 . The methodology proceeds to block  2236  where drive motor  210  and drive clutch  206  are turned off and the PSDI subroutine is terminated. The methodology then loops back to decision block  2004 . 
     Returning to decision block  2224 , if the value in the HEC is not greater than C 2 , the methodology proceeds to decision block  2240  where the status of hold open switch  964  is evaluated. If hold open switch  964  is not open indicating that sliding door  36  is not in the full open position, the methodology proceeds to block  2232 . If hold open switch  964  is open, the methodology proceeds to decision block  2244  where the methodology determines if sliding door  36  has contacted an obstacle. If sliding door  36  has not contacted an obstacle, the methodology proceeds to decision block  2248  where the status of the C 55  command is evaluated. If a new C 55  command has been issued in decision block  2248 , the methodology proceeds to bubble  2132  and proceeds along branch  3 b as described above. If a new C 55  command has not been issued in decision block  2248 , the methodology loops back to decision block  2224 . 
     Referring back to decision block  2244 , if sliding door  36  has contacted an obstacle, the methodology proceeds to block  2252  where the present direction of drive motor  210  is reversed. The methodology proceeds to decision block  2256 . 
     In decision block  2256 , the methodology determines if sliding door  36  has contacted a second obstacle within a predetermined time interval (T 2 ). If sliding door has contacted an obstacle within T 2 , the methodology proceeds to block  2260  where a DTC is stored in control module  54  which aids in the trouble shooting of power sliding door system  10 , but which does not disable the operation of sliding door  36  in a fully automatic mode. The methodology proceeds to block  2236  and progresses as described above. 
     Returning to decision block  2256 , if sliding door  36  has not contacted a second obstacle within T 2 , the methodology proceeds to bubble  2264  and progresses along branch  3   f.  With brief reference to FIG. 36, the methodology proceeds from bubble  2264  to block  2140  and progresses as described above. 
     Referring back to decision block  2124 , if the speed of drive motor  210  is greater than SPD, the methodology proceeds to block  2266  where cinch motor  412  and cinch clutch  416  are turned off. The methodology then proceeds to block  2204  and progresses as described above. 
     Returning to decision block  2020 , if ratchet switch  282  is open, the methodology proceeds to decision block  2268  where the status of hold open switch  964  is evaluated. If hold open switch  964  is open, the methodology proceeds to decision block  2272  where the status of lock switch  714  is evaluated. If lock switch  714  is open in decision block  2272 , the methodology proceeds to block  2088  as described above. If lock switch  714  is not open in decision block  2272 , the methodology loops back to decision block  2004 . 
     Returning to decision block  2268 , if hold open switch  964  is not open, the methodology proceeds to decision block  2276  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is not being operated in either an opening cycle or a closing cycle, the methodology proceeds to block  2280  where a DTC is stored in the memory of control module  54  which aids technicians in evaluating failures in the power sliding door system  10  and also causes control module  54  to disable the automatic operation of sliding door  36 . If, however, sliding door  36  is operating in either an opening cycle or a closing cycle in decision block  2276 , the methodology loops back to decision block  2004 . 
     Referring back to decision block  2016 , if pawl switch  280  is not open, the methodology proceeds to decision block  2284  where the status of ratchet switch  282  is evaluated. If ratchet switch is open, the methodology proceeds to decision block  2288  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is being operating in either an opening cycle or a closing cycle, the methodology loops back to decision block  2004 . If sliding door  36  is not being operating in either an opening cycle or a closing cycle in decision block  2288 , the methodology proceeds to block  2292  where a DTC is stored in the memory of control module  54  which aids technicians in evaluating failures in the power sliding door system  10  and also causes control module  54  to disable the automatic operation of sliding door  36 . 
     Referring back to decision block  2284 , if ratchet switch  282  is open, the methodology proceeds to decision block  2296  where the status of hold open switch  964  is evaluated. If hold open switch is open, the methodology proceeds to decision block  2300  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is not being operating in either an opening cycle or a closing cycle, the methodology proceeds to block  2304  where the methodology determines that sliding door  36  is being operated manually. The methodology then loops back to decision block  2004 . Returning to decision block  2300 , if sliding door  36  is being operating in either an opening cycle or a closing cycle, the methodology proceeds to decision block  2308 . 
     In decision block  2308 , if sliding door is not being operated in an opening cycle, the methodology proceeds to decision block  2312  where the value in the HEC is evaluated. If the value in the HEC is greater than C 1 , the methodology proceeds to bubble  2316  and proceeds along branch  2   d.  With brief reference to FIG. 36, the methodology proceeds from bubble  2316  to decision block  2188  and progresses as described above. Returning to decision block  2312  in FIG. 35, if the value in the HEC is not greater than C 1 , the methodology proceeds to bubble  2320  and progresses along branch  2   e.  With brief reference to FIG. 36, the methodology proceeds from bubble  2320  to decision block  2176  and progresses as described above. 
     Referring back to decision block  2308  in FIG. 35, if sliding door  36  is not being operated in an opening cycle, the methodology proceeds to decision block  2324  where the value in the HEC is evaluated. If the value in the HEC is not greater than C 3 , the methodology proceeds to decision block  2212  and progresses as described above. If the value in the HEC is greater than C 3 , the methodology proceeds to decision block  2248  and progresses as described above. 
     Returning to decision block  2296 , if hold open switch  964  is not open, the methodology proceeds to block  2328  where the HEC is set to 0. The methodology proceeds to block  2332  where cinch motor  412  and cinch clutch  416  are turned on and the cinch latch timer is started. The methodology proceeds to decision block  2336  where the status of hold open switch  964  is evaluated. If hold open switch  964  is not open, the methodology proceeds to decision block  2340  where the value in the cinch latch timer is evaluated. 
     If the value in the cinch latch timer is not greater than T 2 , the methodology loops back to decision block  2336 . If the value in the cinch latch timer is greater than T 2 , the methodology proceeds to block  2344  where cinch motor  412  and cinch clutch  416  are turned off. The methodology proceeds to block  2352  where a DTC is stored in the memory of control module  54  which aids technicians in evaluating failures in the power sliding door system  10  and also causes control module  54  to disable the automatic operation of sliding door  36 . 
     Referring back to decision block  2336 , if hold open switch  964  is open, the methodology proceeds to block  2356  where drive clutch  206  is turned on. The methodology next proceeds to block  2360  where drive motor  210  is turned on and the PSDI subroutine is started. The methodology then proceeds to decision block  2364  where the speed of drive motor  210  is evaluated. If the speed of drive motor  210  is not greater than SPD, the methodology proceeds to block  2368  where a DTC is stored in control module  54  which aids in the trouble shooting of power sliding door system  10 , but which does not disable the operation of sliding door  36  in a fully automatic mode. The methodology proceeds to block  2196  and progresses as described above. 
     Returning to decision block  2364 , if the speed of drive motor  210  is greater than SPD, the methodology proceeds to block  2372  where cinch motor  412  and cinch clutch  416  are turned off. The methodology proceeds to bubble  2376  and progresses along branch  4 . With brief reference to FIG. 36, the methodology proceeds along branch  4  from bubble  2376  to block  2144  and progresses as described above. 
     With reference to FIG. 37, the PSDI subroutine is entered through bubble  3000  and proceeds to decision block  3004  where the methodology determines if ignition switch  980  is being operated to start engine  42 . If ignition switch  980  is being operated to start engine  42 , the methodology proceeds to decision block  3008  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is not being operated in either an opening cycle or a closing cycle, the methodology loops back to bubble  3000 . If sliding door  36  is being operated in either an opening cycle or a closing cycle, the methodology proceeds to block  3012  where control module  54  determines if drive motor  210  or cinch motor  412  and cinch clutch  416  are operating and halts their operation. The methodology loops back to bubble  3000 . 
     If ignition switch  980  is not being operated to start engine  42  in decision block  3004 , the methodology proceeds to decision block  3014  where the methodology determines whether a fuel door  3015  pivotably coupled to vehicle body  14  is in an open position in the path of sliding door  36 . Preferably, the methodology determines the position of fuel door  3015  from a fuel door position sensor  3015   a  which produces a fuel door position sensor signal indicative of the position of fuel door  3015 . Preferably, fuel door position sensor  3015   a  is a limit switch which produces a digital signal in response to the placement of fuel door  3015  into or removal of fuel door  3015  from its closed position. Alternatively, the obstacle detection methodology may also be employed to determine whether fuel door  3015  has been positioned in the path of sliding door  36 . If the methodology determines that fuel door  3015  has been placed in the path of sliding door  36 , the methodology proceeds to decision block  3008  and proceeds as described above. If fuel door  3015  has not been placed in the path of sliding door  36 , the methodology proceeds to decision block  3016 . 
     In decision block  3016  the methodology determines if the operation of sliding door  36  was interrupted by the operation of ignition switch  980  or the placement of fuel door  3015  in the path of sliding door  36 . If the operation of sliding door  36  was not interrupted by the operation of ignition switch  980  or the placement of fuel door  3015 , the methodology proceeds to decision block  3024 . If the operation of sliding door  36  was interrupted by the operation of ignition switch  980  or the placement of fuel door  3015 , the methodology proceeds to block  3020  where control module  54  causes drive motor  210  or cinch motor  412  and cinch clutch  416  to resume their operation. The methodology proceeds to decision block  3024 . 
     In decision block  3024 , the methodology determines if vehicle  12  is being operated in one of the park and neutral gear settings. If vehicle  12  is not being operated in one of the park and neutral gear settings, the methodology proceeds to decision block  3028  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is not being operated in either an opening cycle or a closing cycle, the methodology loops back to decision block  3004 . If sliding door  36  is being operated in either an opening cycle or a closing cycle, the methodology proceeds to block  3032  where the methodology determines if sliding door  36  is being operated in an opening cycle. If sliding door  36  is not being operated in an opening cycle, the methodology loops back to decision block  3004 . If sliding door  36  is being operated in an opening cycle, the methodology proceeds to block  3036  where the current direction of drive motor  210  is reversed and the logic for the HEC is adjusted to alter the value in the HEC in accordance with the new direction in which sliding door  36  is being moved. The methodology then loops back to decision block  3004 . 
     Returning to decision block  3024 , if vehicle  12  is being operated in one of the park and neutral gear settings, the methodology proceeds to decision block  3048  where the methodology evaluates the speed of vehicle  12 . If the speed of vehicle is not approximately 0 miles per hour, the methodology proceeds to decision block  3028 . If the speed of vehicle  12  is approximately 0 miles per hour in decision block  3048 , the methodology proceeds to decision block  3052  where the status of child guard switch  966  is evaluated. If child guard switch  966  is open, the methodology proceeds to decision block  3056  where the methodology determines if the C 55  command to initiate the automatic actuation of sliding door  36  was issued in response to a request from internal switch  134 ′. If the C 55  command was issued in response to a request from internal switch  134 ′, the methodology proceeds to block  3060  where drive motor  210 , drive clutch  206 , cinch motor  412  and cinch clutch  416  are turned off. The methodology then loops back to decision block  3004 . If the C 55  command was not issued in response to a request from internal switch  134 ′, the methodology proceeds to decision block  3064  where the status of handle switch  146  is evaluated. If handle switch  146  is open, the methodology proceeds to block  3060 . If handle switch  146  is not open, the methodology proceeds to decision block  3068  where the methodology determines if sliding door  36  is being operated in either an opening cycle or a closing cycle. If sliding door  36  is not being operated in either an opening cycle or a closing cycle, the methodology proceeds to bubble  3072  where the subroutine terminates. If sliding door  36  is being operated in either an opening cycle or a closing cycle, the methodology loops back to decision block  3004 . 
     While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the description of the appended claims.