Abstract:
A throttle diagnostic system comprises a diagnostic device comprising a throttle sweep diagnostic module that generates N throttle position commands at a first predetermined interval, wherein the N throttle position commands differ by a predetermined interval. A vehicle control system comprises a throttle body assembly that receive the N throttle position commands and a throttle diagnostic module that performs diagnostics on the throttle body assembly at a second predetermined interval that is less than the first predetermined interval.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/256,612, filed on Oct. 30, 2009. The disclosure of the above application is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure relates to diagnostic systems and methods for engine control systems, and more particularly to diagnostic systems and methods for throttle body assemblies. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     Vehicles typically include a throttle assembly that includes a throttle blade that is adjusted by a motor. A throttle position sensor senses a position of the throttle blade. In many vehicles, the throttle position of the throttle blade changes in a one-to-one relationship with changes in position of an accelerator pedal. 
     More recently, some vehicles employ a different control strategy in which the accelerator pedal position to throttle position mapping is not a one-to-one relationship. For example only, torque-based control systems may not have the one-to-one relationship. 
     In these types of systems, it is unlikely that every operating point of the throttle body may be encountered during use. If a problem with the throttle body occurs at one of the unlikely operating points, a vehicle diagnostic system and/or technician may be unable to accurately diagnose faults in the throttle body assembly. 
     SUMMARY 
     A throttle diagnostic system includes a diagnostic device comprising a throttle sweep diagnostic module that generates N throttle position commands at a first predetermined interval. The N throttle position commands differ by a predetermined interval. N is an integer greater than or equal to 25. A vehicle control system comprises a throttle body assembly that receives the N throttle position commands. A throttle diagnostic module performs diagnostics on the throttle body assembly at a second predetermined interval that is less than the first predetermined interval. 
     In other features, the N throttle position commands are equally spaced between a minimum throttle position and a maximum throttle position. The minimum throttle position is 0% and the maximum throttle position is 100%. The predetermined interval is 1%. The first predetermined period is between 1.25 and 1.5 times the second predetermined period. The first predetermined period is between approximately 250 and 300 ms and the second predetermined period is approximately 200 ms. 
     A throttle diagnostic system comprises a throttle sweep diagnostic module that sends N throttle position commands at a first predetermined interval to a throttle body assembly. The N throttle position commands differ by a predetermined interval. N is an integer greater than or equal to 25. A throttle diagnostic module performs diagnostics on the throttle body assembly at a second predetermined interval that is less than the first predetermined interval. 
     In other features, the N throttle position commands are equally spaced between a minimum throttle position and a maximum throttle position. The minimum throttle position is 0% and the maximum throttle position is 100%. The predetermined interval is 1%. The first predetermined period is between 1.25 and 1.5 times the second predetermined period. The first predetermined period is between approximately 250 and 300 ms and the second predetermined period is approximately 200 ms. 
     In still other features, the systems and methods described above are implemented by a computer program executed by one or more processors. The computer program can reside on a tangible computer readable medium such as but not limited to memory, nonvolatile data storage, and/or other suitable tangible storage mediums. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of an exemplary throttle body sweep diagnostic system according to the present disclosure; 
         FIG. 2  is a functional block diagram of another exemplary throttle body sweep diagnostic system according to the present disclosure; and 
         FIG. 3  illustrates steps of a method for performing a throttle body sweep diagnostic system according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure. 
     As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     Conventional throttle diagnostic tests are not typically repeatable. Some conventional throttle diagnostic tests require manual operation of the accelerator pedal. Other tests provide manual selection of course throttle increments such as 10% increments. The diagnostic system may only detect a fault if the throttle position is maintained during a diagnostic window such as 200 ms. These manual types of tests often fail to properly diagnose the fault. 
     A throttle sweep diagnostic system and method according to the present disclosure performs a throttle diagnostic sweep test. A vehicle control system or a diagnostic device performs the throttle diagnostic sweep test. The throttle diagnostic sweep test sweeps the throttle position from a minimum position to a maximum position (or vice versa) via predetermined throttle increments at predetermined intervals. 
     The throttle diagnostic sweep test leaves the throttle position at a new setting for a first predetermined period that is longer than a second predetermined period required by an on-board diagnostic system of the vehicle control system to diagnose a fault. The predetermined throttle increments are selected to be sufficiently small to identify throttle motor faults such as faults in a commutator of a motor (used to position the throttle blade) or sensor tracks of a throttle position sensor (used to sense a position of the throttle blade). 
     Referring now to  FIG. 1 , a vehicle diagnostic system  10  includes a diagnostic device  20  and a vehicle control system  24 . The diagnostic device  20  includes an interface  26  that communicates with an interface  28  of the vehicle control system  24 . For example only, the interfaces  26  and  28  can be On-Board Diagnostic (OBD)-complaint ports, assembly line data links (ALDLs), universal serial bus (USB) interfaces, and/or any other suitable interfaces. 
     The diagnostic device  20  further includes a processing module  34  that provides data and control processing. The diagnostic device  20  further includes a throttle sweep diagnostic module  36  that sends throttle position commands at predetermined intervals and checks for diagnostic codes being set as will be described further below. The diagnostic device  20  further includes a display  38  and an input device  42  such as a keyboard, touch screen and/or other suitable input device. 
     The vehicle control system  24  further includes a control module  48  that includes a throttle diagnostic module  50 . The control module  48  may be implemented by the engine control module or any other suitable vehicle control module. The control module  48  communicates with a throttle body assembly  52  that includes a throttle blade motor  54  and a throttle position sensor  56 . The commanded throttle position is sent to the throttle blade motor  54 . The throttle position sensor  56  senses a position of a throttle blade (not shown). 
     The throttle diagnostic module  50  compares a commanded throttle position sent to the throttle blade motor  54  with an actual throttle position sensed by the throttle position sensor  56 . If the difference between the commanded throttle position and the actual throttle position is outside of a predetermined range, takes too long to reach the correct position, fails to settle or fails to meet any other calibration parameter, the throttle diagnostic module  50  triggers a fault. 
     Typically, the throttle diagnostic module  50  performs a diagnostic routine once every predetermined period. In other words, the throttle diagnostic module  50  determines whether or not the throttle body assembly is operational or not operational once every predetermined period or within a predetermined period after a new throttle position is commanded. Each of the commanded throttle positions is set and maintained for a sufficient amount of time to allow the throttle diagnostic module to determine if a fault has occurred. 
     Referring now to  FIG. 2 , an alternate implementation of the vehicle control system  60  is shown. In  FIG. 1 , the commanded throttle positions are sent to the vehicle control system  24  from an external diagnostic device. In the implementation in  FIG. 2 , the throttle sweep diagnostic module  68  is integrated with a throttle diagnostic module  66 , which may form part of the control module  64  or any other vehicle control module. The control module  64  may be an engine control module. 
     The throttle sweep diagnostic module  68  operates in a similar manner as described above in conjunction with  FIG. 1 . However, the vehicle control system  60  is able to initiate the throttle sweep test without receiving throttle commands from the external diagnostic device such as the diagnostic device in  FIG. 1 . In some implementations, the diagnostic device may still be used to trigger the test. 
     Referring now to  FIG. 3 , the method  100  begins at  102 . At  104 , the method determines whether or not the vehicle has (or had) an error code in a predetermined set of error codes at  102 . For example, the predetermined set of error codes may include one or more of the following OBD codes: P 1516 , P 2101 , P 2119 , P 2135 , P 0122 , P 0123 , P 0222  and P 0223 . 
     If  102  is true, the method determines whether or not there are any active error codes at  104 . If  104  is true, the error codes are reset at  108 . If the error code was set due to faulty vehicle wiring, the error code will return immediately. Otherwise if the vehicle wiring is not faulty, the code will not return until the throttle sweep test is completed. Thus, both the vehicle wiring and other components are tested. In some implementations, a timer may be added to allow at least one diagnostic period to elapse. After the period is up, control may be used to detect the triggering of the fault before the sweep test is run and a wiring fault may be generated identifying the vehicle wiring as the source of the fault. 
     When  104  is false, the method continues at  112  where the method determines whether a throttle sweep test has been selected via the diagnostic device or by the vehicle control system. If  112  is false, the method ends. 
     If  112  is true, the throttle position is set to a first throttle position at  114 . At  115 , the method waits a first predetermined period. The first predetermined period may be greater than a second predetermined period that is equal to a diagnostic response time of the vehicle control system. 
     At  116 , the method determines whether a diagnostic code has been set. For example only, the diagnostic codes may be OBD codes such as P 2101  or P 1516 . If  116  is true, the method displays a first message on the display  38  of the diagnostic device at  118  and the method ends. For example, the first message may be a message instructing a technician to change the throttle body assembly, a fault code set on the control module of the vehicle or any other indicator. 
     If  116  is false, control increments (or decrements if starting from 100%) the throttle position by a predetermined amount. At  122 , the method waits the first predetermined period. At  126 , control determines whether the throttle blade is at a maximum (or minimum if starting from 100%) throttle position. If  126  is false, control returns to step  116 . If  126  is true, control displays a second message on the diagnostic device at  128 . The second diagnostic message may indicate that the throttle body sweep diagnostic test was passed and the method ends. 
     For example only, the throttle diagnostic sweep test sweeps the throttle from 0% to 100% at 1-4% intervals. The first predetermined period may be between 1.25 and 1.5 times the second predetermined period. For example only, each interval is performed every 250 ms to 300 ms for a total sweep time of less than 25 to 30 seconds. In this example, the on-board diagnostic system diagnoses faults within 200 ms. If there are faults on the commutator of the motor or problems with the throttle position sensor, a resolution of 1-4% is fine enough to catch this type of problem. Therefore, the test includes at least 25 intervals. The test may be run with the engine off and the ignition switch on. 
     If the diagnostic device is used, the test can be run without intrusion into a wire harness or throttle body of the vehicle. The test is repeatable, which allows further investigation into failed parts by a supplier of the throttle body assembly. The test uses standard tools and does not require a special adapter harness, a custom power supply or a signal generator. 
     The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification, and the following claims.