Abstract:
Provided are a vehicle configured such that if idling does not automatically stop, an in-vehicle display will occur immediately if a malfunction is the cause, thereby enabling a driver to have peace of mind and concentrate on driving, without giving the driver an unnecessary sense of unease; a vehicle diagnostic system therefor; and a vehicle diagnostic method. The vehicle comprises an idle stop error display unit provided corresponding to a specific ECU among a plurality of ECUs, and that indicates that an idle stop malfunction has occurred, being a malfunction corresponding to a second IS malfunction code, when a malfunction has occurred within a control target range for any among the plurality of ECUs, said malfunction recording the second IS malfunction code which does not cause the operation of a warning light requesting inspection or repair of an error that has occurred inside the vehicle.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a vehicle including an idling stop control system for executing an idling stop for stopping a drive source such as an engine or the like from idling, by cooperatively controlling a plurality of electronic control units. The present invention also relates to a diagnosing system and a diagnosing method of such a vehicle. 
       BACKGROUND ART 
       [0002]    In the event of some fault occurring in a vehicle while the vehicle is being driven, it has heretofore been customary for an electronic control unit (hereinafter referred to as “ECU”) on the vehicle which deals with the faulty component to record fault information such as a fault code or the like. If a serious fault such as a fault with respect to an engine combustion or exhaust system of the vehicle occurs, it has been the practice to turn on a warning lamp on the instrument panel to let the driver know the occurrence of the fault. 
         [0003]    For example, if an engine coolant temperature sensor of the vehicle fails, then an engine ECU records a fault code “PXXXX” and turns on a PGM-FI warning lamp to indicate the fault to the driver. 
         [0004]    For repairing the vehicle, the repair shop worker connects an external diagnosing apparatus to a data link connector of the vehicle, and reads fault codes accumulated in the engine ECU, which is an ECU concerned with engine coolant temperature faults, to confirm or recognize details of the failure. Therefore, the repair shop worker can spot the location and cause of the failure relatively easily. 
         [0005]    Attempts have been made to let the driver of a vehicle know its states in combination with a system, known as an idling stop control system, that automatically stops the engine of the vehicle from idling when the vehicle comes to a halt based on an overall judgment made in view of various factors including a reduction in fuel consumption. The idling stop control system judges whether the engine should be stopped from idling or not, using various ECUs that cooperatively judge merits and demerits of the engine stopped from idling. When the engine is stopped from idling by the idling stop control system, the fact that the engine is stopped from idling is displayed on an instrument panel, making the driver rest assured at the time the vehicle stops moving (see, for example, Abstract of Japanese Laid-Open Patent Publication No. 2004-224269). 
       SUMMARY OF INVENTION 
       [0006]    However, if the engine of a vehicle with an idling stop control function is not automatically stopped from idling when the vehicle stops moving, then the driver is unable to decide whether the engine keeps idling because the idling stop control function has failed or because some conditions for not stopping the engine from idling have been satisfied. If it frequently happens that the engine is not automatically stopped from idling when the vehicle stops moving, then the driver may have the sense of mistrust that the idling stop control function has failed, and may often be liable to contact the vehicle dealer to ask if the idling stop control function has failed even though it is working properly. 
         [0007]    In order to diagnose a failure of the idling stop control system to stop the engine from idling, it is necessary to individually access all involved ECUs in the vehicle to read fault information such as fault codes recorded in the ECUs by connecting an external diagnosing machine to the ECUs. It is quite time-consuming to extract the necessary information from all those ECUs. In addition, since all the fault information including fault codes is read from the ECUs, it includes fault information that has nothing to do with the idling stop control system, and hence it is also quite time-consuming to verify the extracted fault information. 
         [0008]    The present invention has been made in view of the above difficulties. It is an object of the present invention to provide a vehicle, and a diagnosing system and a diagnosing method of the vehicle, which, when an engine is not automatically stopped from idling, can immediately indicate the cause of non-execution of the idling stop in the interior of the vehicle if a fault is the cause thereof, thereby allowing the driver to concentrate on driving securely without having an unnecessary sense of mistrust. 
         [0009]    According to the present invention, there is provided a vehicle diagnosing system for performing a fault diagnosis of a vehicle including an idling stop control system, the idling stop control system executing an idling stop for stopping a drive source of the vehicle from idling by cooperatively controlling a plurality of electronic control units, wherein the vehicle comprises, a plurality of warning lamps associated with specific ones of the electronic control units, and configured to demand an inspection or repair of a failure which has occurred in the vehicle, and an idling stop controller configured to automatically execute the idling stop when a predetermined condition is satisfied, wherein when the electronic control units detect a fault in target ranges controlled thereby, the electronic control units record fault codes, the fault codes include idling stop fault codes defined as inhibiting the idling stop of the drive source, and non-idling stop fault codes not defined as inhibiting the idling stop, the idling stop fault codes include first idling stop fault codes defined as energizing the warning lamps and second idling stop fault codes not defined as energizing the warning lamps, and the vehicle further comprises an idling stop failure indicator configured to indicate an idling stop fault corresponding to one of the second idling stop fault codes when the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in a target range controlled thereby. 
         [0010]    According to the present invention, the vehicle comprises an idling stop failure indicator configured to indicate an idling stop fault corresponding to one of the second idling stop fault codes when the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in a target range controlled thereby. When a fault has occurred which is not serious enough to energize the warning lamps, but which inhibits an idling stop, the driver of the vehicle can recognize that the fault has occurred based on the indication of the idling stop failure indicator. 
         [0011]    Therefore, even if an idling stop is not executed in a case where the driver of the vehicle tends to expect that the idling stop is carried out, e.g., when the driver waits for the traffic light at an intersection, the driver can simply and visually confirm the indication of the idling stop failure indicator to see if the reason for the non-execution of the idling stop is due to occurrence of the fault or not. Further, on the occurrence of fault, the driver can simply understand that the fault is serious enough to energize a warning lamp or that the fault is a relatively minor fault which corresponds to the second idling stop fault mode and energizes the idling stop failure indicator. Accordingly, the driver can concentrate on driving securely without having an unnecessary sense of mistrust while driving such that the idling stop is not executed properly. 
         [0012]    Further, the driver can recognize the degree of urgency about the fault, case by case. In a repair shop or the like for a fault diagnosis of the vehicle, the second idling stop fault codes can be used as a guide for performing diagnoses on the electronic control units. 
         [0013]    The idling stop failure indicator may include a single indicator lamp, and the idling stop failure indicator may indicate the idling stop fault by the single indicator lamp when the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in the target range controlled thereby. 
         [0014]    Generally, each of warning lamps in the vehicle which demand an inspection or repair of a failure in the vehicle is associated with a specific electronic control unit. Stated otherwise, when an energized warning lamp is specified, the electronic control unit for controlling the failure component can be identified. In contrast, when the second idling stop fault codes are recorded in any of the electronic control units, the single indicator lamp is used for indicating that the idling stop faults have occurred. Thus, only one indicator lamp indicates that the idling stop faults have occurred when any of the electronic control units detect the idling stop faults. Accordingly, the user can easily recognize whether an idling stop failure has occurred or not while the user is driving the vehicle. 
         [0015]    Whether or not the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in the target range controlled thereby, the idling stop is inhibited and the idling stop fault is indicated when an activation count of a starter motor is larger than a predetermined value or when a starting performance of the starter battery for the starter motor is lower than a predetermined value. Even if no fault has occurred in the vehicle, the driver can recognize a risk that the vehicle cannot possibly be started owing to the deterioration of the starter motor or starter battery, through the indication of the idling stop failure indicator. 
         [0016]    According to the present invention, there is also provided a vehicle diagnosing method of performing a fault diagnosis of a vehicle including an idling stop control system, the idling stop control system executing an idling stop for stopping a drive source of the vehicle from idling by cooperatively controlling a plurality of electronic control units, wherein the vehicle comprises a plurality of warning lamps associated with the electronic control units, and configured to demand an inspection or repair of a failure which has occurred in the vehicle, and an idling stop controller configured to automatically execute the idling stop when a predetermined condition is satisfied, wherein when the electronic control units detect a fault in target ranges controlled thereby, the electronic control units record fault codes, the fault codes include idling stop fault codes defined as inhibiting the idling stop of the drive source, and non-idling stop fault codes not defined as inhibiting the idling stop, the idling stop fault codes include first idling stop fault codes defined as energizing the warning lamps and second idling stop fault codes not defined as energizing the warning lamps, and an idling stop failure indicator in the vehicle indicates an idling stop fault corresponding to one of the second idling stop fault codes when the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in a target range controlled thereby. 
         [0017]    According to the present invention, there is also provided a vehicle including an idling stop control system, the idling stop control system executing an idling stop for stopping a drive source of the vehicle from idling by cooperatively controlling a plurality of electronic control units, wherein the vehicle comprises a plurality of warning lamps associated with the electronic control units, and configured to demand an inspection or repair of a failure which has occurred in the vehicle, and an idling stop controller configured to automatically execute the idling stop when a predetermined condition is satisfied, wherein when the electronic control units detect a fault in target ranges controlled thereby, the electronic control units record fault codes, the fault codes include idling stop fault codes defined as inhibiting the idling stop of the drive source, and non-idling stop fault codes not defined as inhibiting the idling stop, the idling stop fault codes include first idling stop fault codes defined as energizing the warning lamps and second idling stop fault codes not defined as energizing the warning lamps, and the vehicle further comprises an idling stop failure indicator configured to indicate an idling stop fault corresponding to one of the second idling stop fault codes when the idling stop fault which records the one of the second idling stop fault codes in any of the electronic control units has occurred in a target range controlled thereby. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  is a block diagram showing a general arrangement of a vehicle diagnosing system according to an embodiment of the present invention; 
           [0019]      FIG. 2  is a view of a meter display device; 
           [0020]      FIG. 3  is a flowchart of a normal processing sequence followed when the engine of a vehicle is automatically stopped from idling at the time the vehicle comes to a halt; 
           [0021]      FIG. 4  is a flowchart of an idling stop control process carried out by an engine electronic control unit (hereinafter referred to as “engine ECU”); 
           [0022]      FIG. 5  is a flowchart of a process (details of S 21  in  FIG. 4 ) carried out by the engine ECU for judging idling stop preconditions (hereinafter referred to as “IS preconditions”); 
           [0023]      FIG. 6  is a diagram illustrating information that is supplied to the engine ECU for the engine ECU to judge IS preconditions and idling stop permitting conditions (hereinafter referred to as “IS permitting conditions”); 
           [0024]      FIG. 7  is a flowchart of a process (details of S 22  in  FIG. 4 ) carried out by the engine ECU for judging IS permitting conditions; 
           [0025]      FIG. 8  is a diagram showing examples of faults corresponding to first IS fault codes, second IS fault codes, and non-IS fault codes; 
           [0026]      FIG. 9  is a first flowchart of an idling stop-related display control process carried out by the engine ECU; 
           [0027]      FIG. 10  is a second flowchart of the idling stop-related display control process carried out by the engine ECU; 
           [0028]      FIG. 11  is a flowchart of a sequence followed when a fault diagnosis is performed on the vehicle using an external diagnosing apparatus; 
           [0029]      FIG. 12  is a view showing by way of example a screen displayed when the external diagnosing apparatus confirms various components of the vehicle while an idling stop indicator lamp (hereinafter referred to as “IS indicator lamp”) is being lighted in red; 
           [0030]      FIG. 13  is a view showing by way of example a screen displayed when the external diagnosing apparatus confirms various components of the vehicle while the IS indicator lamp is not being lighted in red; 
           [0031]      FIG. 14  is a flowchart of a process carried out by the external diagnosing apparatus for confirming the states of various components of the vehicle if the IS indicator lamp is lighted in red; and 
           [0032]      FIG. 15  is a flowchart of a processing sequence carried out by the external diagnosing apparatus for confirming the states of various components of the vehicle the IS indicator lamp is not lighted in red. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     A. Embodiment 
     [1. Arrangement] 
     (1-1. Overall Arrangement) 
       [0033]      FIG. 1  shows in block form a general arrangement of a vehicle diagnosing system  10  (hereinafter referred to as “system  10 ”) according to an embodiment of the present invention. As shown in  FIG. 1 , the system  10  includes a vehicle  12  as a diagnostic target and an external diagnosing apparatus  14  for diagnosing the condition of the vehicle  12  from outside of the vehicle  12 . The condition of the vehicle  12  can be self-diagnosed. 
       (1-2. Vehicle  12 ) 
     (1-2-1. Vehicle  12  in Its Entirety) 
       [0034]    The vehicle  12  is a diesel-powered vehicle having an engine  16  and also a manual transmission (MT) vehicle. As described later, the vehicle  12  may be a gasoline-powered vehicle (including a hybrid vehicle) or an electric vehicle (including a fuel cell vehicle). The vehicle  12  may be a vehicle other than an MT vehicle, e.g., an automatic transmission vehicle (AT vehicle). The vehicle  12  according to the present embodiment is a four-wheeled vehicle. However, the vehicle  12  may be a two-wheeled vehicle, a three-wheeled vehicle, a six-wheeled vehicle, or the like. 
         [0035]    The vehicle  12  has a plurality of electronic control units (hereinafter referred to as “ECUs”) for controlling the vehicle  12 . Specifically, the vehicle  12  has an engine electronic control unit (hereinafter referred to as “engine ECU  20 ” or ENG ECU  20 ), a vehicle stability assistance electronic control unit (hereinafter referred to as “VSA ECU  22 ”), an antilock brake system electronic control unit (hereinafter referred to as “ABS ECU  24 ”), a brake negative pressure electronic control unit (hereinafter referred to as “brake negative pressure ECU  26 ”), an electric power steering electronic control unit  28  (hereinafter referred to as “EPS ECU  28 ”), a battery electronic control unit (hereinafter referred to as “battery ECU  30 ”), a meter electronic control unit (hereinafter referred to as “meter ECU  32 ”), an air conditioner electronic control unit (hereinafter referred to as “air conditioner ECU  34 ”), a supplemental restraint system electronic control unit (hereinafter referred to as “SRS ECU  36 ”), and an immobilizer electronic control unit (hereinafter referred to as “immobilizer ECU  38 ”). 
       (1-2-2. Engine ECU  20  and Its Periphery) 
       [0036]    The engine ECU  20  (idling stop controller), which serves to control the output power of the engine  16 , has, in addition to its engine control function, a function to control an idling stop (hereinafter also referred to as “IS”) of the engine  16  based on an overall judgment made about the results that are obtained by the respective ECUs when they have judged whether the engine  16  should be stopped from idling or not depending on the states of the respective control targets of the ECUs. The engine ECU  20  also controls an alternator  40  and a starter motor  42  in addition to the engine  16  (described in detail later). When actuated by the engine  16 , the alternator  40  generates electric power and supplies the generated electric energy to a 12 V battery  86  to be described later, etc. For starting the engine  16 , the starter motor  42  rotates a crankshaft, not shown, to start the engine  16 . 
         [0037]    The engine ECU  20  is supplied with output signals from a coolant temperature sensor  44 , an accelerator pedal sensor  46 , a brake pedal sensor  48 , a clutch pedal sensor  50 , a shift position sensor  52 , a vehicle speed sensor  54 , and an idling stop controller turn-off switch  56  (hereinafter referred to as “IS off SW  56 ”). 
         [0038]    The coolant temperature sensor  44  detects the temperature of the coolant of the engine  16  (hereinafter referred to as “engine coolant temperature Tw”). The accelerator pedal sensor  46  detects an operated amount of an accelerator pedal  58  (hereinafter referred to as “accelerator operated amount θap”). The brake pedal sensor  48  detects an operated amount of a brake pedal  60  (hereinafter referred to as “brake operated amount θbp”). The clutch pedal sensor  50  detects an operated amount of a clutch pedal (hereinafter referred to as “clutch operated amount θcp”). The shift position sensor  52  detects an operated position of a shift lever  64  (hereinafter referred to as “shift position Ps”). The vehicle speed sensor  54  detects a vehicle speed V of the vehicle  12 . 
         [0039]    The IS off SW  56  is a switch for setting whether an automatic idling stop control function is to be activated or not, and is located in a position operable by the driver of the vehicle  12 . When the IS off SW  56  is turned off, the engine ECU  20  is capable of automatically stopping the engine  16  from idling. When the IS off SW  56  is turned on, the automatic idling stop control function is inactivated, and the engine ECU  20  is inhibited from stopping the engine  16  from idling. 
         [0040]    As shown in  FIG. 6 , the engine ECU  20  has an input/output unit  70 , a processor  72 , and a memory  74 . Although not shown, each of the other ECUs also has an input/output unit, a processor, and a memory. 
       (1-2-3. VSA ECU  22  and ABS ECU  24 ) 
       [0041]    The VSA ECU  22  serves to perform a vehicle stability assistance (vehicle stability assist) control process. The VSA ECU  22  controls a brake system, etc., not shown, to stabilize the behavior of the vehicle  12  when the vehicle  12  turns along a curved road or the like. 
         [0042]    The ABS ECU  24  serves to perform an antilock braking control process. The ABS ECU  24  controls the brake system, etc. to prevent the road wheels, not shown, of the vehicle  12  from being locked when the vehicle  12  is braked. 
       (1-2-4. Brake Negative Pressure ECU  26 ) 
       [0043]    The brake negative pressure ECU  26  controls the negative pressure of the brake system based on a brake negative pressure Pn detected by a negative pressure sensor  80 . The brake negative pressure Pn will hereinafter be described as having a positive value. 
       (1-2-5. EPS ECU  28  and Its Periphery) 
       [0044]    The EPS ECU  28  serves to perform a steering assistance control process. The EPS ECU  28  controls the components (an electric motor and a torque sensor, both not shown, a steering angle sensor  82 , etc.) of an electric power steering apparatus to assist the driver in steering the vehicle  12 . The steering angle sensor  82  detects a steering angle θst of a steering wheel  84 . 
       (1-2-6. Battery ECU  30  and Its Periphery) 
       [0045]    The battery ECU  30  controls the charging and discharging, etc. of the 12 V battery  86  (hereinafter also referred to as “battery  86 ” or “12 V BAT  86 ”). The 12 V battery  86  supplies electric power to the various electric components (the ECUs, the sensors, an air conditioner  180 , etc.) of the vehicle  12  through electric power cables, not shown. 
       (1-2-7. Meter ECU  32  and Its Periphery) 
       [0046]    The meter ECU  32  controls a meter display device  92  on an instrument panel  90  (see  FIG. 2 ). 
         [0047]      FIG. 2  is a view of the meter display device  92 . As shown in  FIG. 2 , the meter display device  92  has first through fifth display units  94 ,  96 ,  98 ,  100 ,  102 . The first display unit  94  displays a vehicle speed V in a digital presentation. The second display unit  96  displays an engine rotational speed [rpm] and has a plurality of warning lamps  104 ,  106  and a plurality of indicator lamps  108 ,  110 ,  112 . 
         [0048]    The warning lamp  104 , which is a VSA warning lamp, blinks when a VSA function is working and is lighted when the VSA function suffers a fault, or stated otherwise, when a fault occurs within a target range that is controlled by the VSA ECU  22 . The warning lamp  106  is a VSA off warning lamp that is lighted when the VSA function is turned off by an operating switch, not shown. 
         [0049]    The indicator lamp  108  is a shift-up indicator lamp that is lighted when a shift-up operation is recommended. The indicator lamp  110  is a shift-down indicator lamp that is lighted when a shift-down operation is recommended. 
         [0050]    The indicator lamp  112  is an idling stop indicator lamp (hereinafter referred to as “IS indicator lamp  112 ”) for indicating whether an IS control process is being carried out or not. According to the present embodiment, the IS indicator lamp  112  is lighted or blinks and changes its light emission colors depending on how the IS control process is carried out, as described in detail later with reference to  FIGS. 9 and 10 , etc. 
         [0051]    According to the present embodiment, a “warning lamp” is provided to give a warning, e.g., for prompting the driver to inspect a fault or repair the vehicle  12  or take a certain action, in the event of a fault occurring in the vehicle  12 , and is associated with a specific ECU, sensor, or switch. The “warning lamp” is also used to give a warning about the occurrence of a significant fault that is directly related to a failure (system failure) tending to make the entire target range controlled by each ECU fail to function. Therefore, anyone who sees a warning lamp that is lighted, they can understand which ECU, sensor, or switch is involved in the warning for prompting them to inspect a fault or repair the vehicle  12  or take a certain action. 
         [0052]    If a “warning lamp” is related to a failure or fault in the vehicle  12 , then once such a failure or fault occurs, the warning lamp continues to operate, i.e., to be lighted or to blink until the failure or fault is eliminated. The warning lamp is de-energized when an ignition switch, not shown, of the vehicle  12  is turned off, but starts to continue operating again when the ignition switch is turned on. 
         [0053]    According to the present embodiment, an “indicator lamp” is provided to indicate a certain content without giving a warning from a warning lamp. For example, an “indicator lamp” is used to indicate other events than a warning about the occurrence of a significant fault that is directly related to a system failure, e.g., the occurrence of a relatively minor fault that is not directly related to a system failure. 
         [0054]    The third display unit  98  displays an engine coolant temperature Tw and has a plurality of warning lamps  120 ,  122 ,  124 ,  126  and a plurality of indicator lamps  128 ,  130 ,  132 ,  134 ,  136 ,  138 ,  140 ,  142 . 
         [0055]    The warning lamp  120  is a PGM-FI warning lamp (engine warning lamp) that is lighted or blinks when a fault is occurring in relation to the engine  16 , or stated otherwise, when a fault is occurring within a target range controlled by the engine ECU  20 . The warning lamp  122  is a charge warning lamp that is lighted when the 12 V battery  86  is not charged enough and is also lighted when a fault is occurring in relation to the 12 V battery  86 , or stated otherwise, when a fault is occurring within a target range controlled by the battery ECU  30 . 
         [0056]    The warning lamp  124  is an oil pressure warning lamp that is lighted when the pressure of the engine oil drops and is also lighted when a fault is occurring in relation to the pressure of the engine oil, or stated otherwise, when a fault is occurring within a target range controlled by an oil pressure control ECU, not shown, while the engine  16  is in operation. 
         [0057]    The warning lamp  126  is a brake warning lamp that is lighted when a parking brake, not shown, is applied and is also lighted when a fault is occurring in relation to the brake system, or stated otherwise, when a fault is occurring within a target range controlled by a brake ECU, not shown. 
         [0058]    The indicator lamp  128  is a high-beam indicator lamp which is lighted when a head light, not shown, is directed upwardly. The indicator lamp  132  is a light turn-on indicator lamp that is lighted unless a light switch, not shown, is turned off. The indicator lamp  134  is a fog light turn-on indicator lamp that is lighted when a fog light, not shown, is turned on. 
         [0059]    The fourth display unit  100  indicates a remaining level of fuel and has a plurality of warning lamps  150 ,  152 ,  154 ,  156 ,  158 ,  160 ,  162  and a plurality of indicator lamps  164 ,  166 ,  168 ,  170 ,  172 ,  174 . 
         [0060]    The warning lamp  150  is an ABS warning lamp that is lighted when an ABS function is suffering a fault, or stated otherwise, a fault is occurring within a target range controlled by the ABS ECU  24 . The warning lamp  152  is an EPS warning lamp that is lighted when the electric power steering apparatus, not shown, is suffering a fault, or stated otherwise, when a fault is occurring within a target range controlled by the EPS ECU  28 . The warning lamp  154  is a smart key system warning lamp that is lighted when a smart key system, not shown, is suffering a fault, or stated otherwise, when a fault is occurring within part of a target range controlled by the immobilizer ECU  38 . The warning lamp  156  is a door opening and closing warning lamp that is lighted when a door  192  ( FIG. 1 ) is not completely closed. 
         [0061]    The warning lamp  158  is a remaining fuel level warning lamp that is lighted when the remaining level of fuel is low and is also lighted when a fuel meter is suffering a fault. The warning lamp  160  is an airbag system warning lamp that is lighted when an airbag system, not shown, or a pretensioner system, not shown, is suffering a fault, or stated otherwise, when a fault is occurring within part of a target range controlled by the SRS ECU  36 . The warning lamp  162  is a seatbelt unfastened warning lamp that is lighted when the driver has not fastened a seatbelt  190  and is also lighted when a fault is occurring in relation to the seatbelt  190 , stated otherwise, when a fault is occurring within part of the target range controlled by the SRS ECU  36 . 
         [0062]    The indicator lamp  164  is an economy mode indicator lamp that is lighted when an economy mode is selected as a drive mode of the vehicle  12  by a switch, not shown. The indicator lamp  172  is an immobilizer system indicator lamp that blinks when the immobilizer ECU  38  is unable to recognize key information. 
         [0063]    The indicator lamp  174  is a side airbag automatic shutdown indicator lamp that is lighted when a sensor, not shown, of a side airbag system on a front passenger seat is operated and the side airbag system is automatically shut down. 
         [0064]    The fifth display unit  102 , which comprises a so-called multi-information display (MID) having a display panel such as a liquid crystal panel or an organic EL panel, is capable of displaying various items of information such as messages, etc. depending on commands from the meter ECU  32 . 
       (1-2-8. Air Conditioner ECU  34  and Its Periphery) 
       [0065]    The air conditioner ECU  34  ( FIG. 1 ) controls the air conditioner  180 . 
       (1-2-9. SRS ECU  36  and Its Periphery) 
       [0066]    The SRS ECU  36  controls the airbag system, not shown. The SRS ECU  36  is supplied with output signals from an engine hood sensor  182 , a seatbelt sensor  184 , and a door sensor  186 . The engine hood sensor  182  detects whether an engine hood  188  is closed or opened. The seatbelt sensor  184  detects whether the seatbelt  190  is fastened or not. The door sensor  186  detects whether the door  192  is opened or closed. 
       (1-2-10. Immobilizer ECU  38  and Its Periphery) 
       [0067]    The immobilizer ECU  38  controls an immobilizer system, not shown, and the smart key system, not shown. 
       (1-3. External Diagnosing Apparatus  14 ) 
       [0068]    The external diagnosing apparatus  14  can perform various diagnoses (including a fault diagnosis) on the vehicle  12 . As shown in  FIG. 1 , the external diagnosing apparatus  14  has a communication cable  200 , an input/output unit  202 , an operating unit  204 , a processor  206 , a memory  208 , and a display unit  210 . 
         [0069]    The communication cable  200  is connected to a data link connector  194  of the vehicle  12  for communication with the vehicle  12 . The communication cable  200  may be replaced with a wireless communication function. The input/output unit  202  is used not only for communication with the vehicle  12 , but also for sending data to and receiving data from other external devices, e.g., an external server. The operating unit  204  includes a keyboard, a mouse, a touch pad, etc., not shown. 
         [0070]    The processor  206  performs various control processes for diagnosing the vehicle  12 . The memory  208  stores programs and data to be executed and used by the processor  206 , and comprises a nonvolatile memory and a volatile memory. The display unit  210  displays operating screens and diagnostic results of the external diagnosing apparatus  14 . 
         [0071]    The external diagnosing apparatus  14  may comprise a laptop personal computer, a tablet computer, or a smart phone that is commercially available, for example. The external diagnosing apparatus  14  may not necessarily be in the form of a single unit, but may be a combination of a personal computer as a main unit and a slave unit (tester) as an interface with the vehicle  12 . 
       [2. Control Process in Relation to Idling Stop of the Vehicle  12 ] 
     (2-1. Normal Flow Overview) 
       [0072]      FIG. 3  is a flowchart of a normal processing sequence followed when the engine of the vehicle  12  is automatically stopped from idling at the time the vehicle  12  comes to a halt. When the vehicle  12  comes to a halt at a red traffic signal (step S 1 ), the driver depresses the clutch pedal  62  and then changes the shift position Ps to a neutral position “N” (step S 2 ). Thereafter, the driver releases the clutch pedal  62  (step S 3 ). The engine  16  is now automatically stopped from idling (step S 4 ), and the IS indicator lamp  112  of the meter display device  92  is lighted in green, indicating that the engine  16  is being stopped from idling (step S 5 ). 
         [0073]    When the red traffic signal changes from a red traffic signal to a green traffic signal (step S 6 ), the driver depresses the clutch pedal  62  (step S 7 ). The engine is no longer stopped from idling, but is restarted by the starter motor  42  that has been automatically activated (step S 8 ). The IS indicator lamp  112  is turned off, indicating that the engine  16  is not stopped from idling (step S 9 ). The driver moves the shift lever  64  to bring the shift position Ps to a drive position, e.g., a first speed position, causing the vehicle  12  to start moving (step S 10 ). 
       (2-2. Idling Stop Control Process of the Engine ECU  20 ) 
     (2-2-1. Overall Flow) 
       [0074]    A control process, i.e., an idling stop control process, carried out by the engine ECU  20  during the flow shown in  FIG. 3  will be described below. 
         [0075]      FIG. 4  is a flowchart of an idling stop control process carried out by the engine ECU  20 . In step S 21 , the engine ECU  20  judges whether a precondition for stopping the engine  16  from idling (hereinafter referred to as “IS precondition”) is satisfied or not. 
         [0076]    The IS precondition is satisfied when the shift lever  64  is moved to the neutral position (S 2  in  FIG. 3 ) and the clutch pedal  62  is released, or stated otherwise, the clutch operated amount θcp becomes equal to or smaller than a predetermined value (S 3  in  FIG. 3 ), for example. In addition or alternatively, the IS precondition may be satisfied when another action is taken by the driver, e.g., at least one of the conditions where the accelerator pedal  58  is released, or stated otherwise, the accelerator operated amount θap becomes equal to or smaller than a predetermined value, and where the brake pedal  60  is depressed, or stated otherwise, the brake operated amount θbp becomes equal to or greater than a predetermined value, and where the vehicle  12  is traveling in a certain running state, e.g., when the vehicle speed V is equal to or smaller than a predetermined value. 
         [0077]    In other words, the IS precondition may include at least one condition that serves as a basis for stopping the engine  16  from idling, i.e., a condition for judging a situation where the engine  16  is expected to stop idling or a situation suitable for stopping the engine  16  from idling. Such a condition includes a condition that can be recognized by the driver for driving the vehicle  12 . 
         [0078]    Details of step S 21  according to the present embodiment will be described later with reference to  FIG. 5 . 
         [0079]    In step S 22 , the engine ECU  20  judges whether an idling stop permitting condition (hereinafter referred to as “IS permitting condition”) is satisfied or not. Whereas the IS precondition is a precondition for stopping the engine  16  from idling, e.g., at least one of an action taken by the driver and a running state of the vehicle  12 , the IS permitting condition is a condition for not permitting the engine  16  to stop idling even if the precondition for stopping the engine  16  from idling is satisfied, e.g., a condition about the occurrence of a failure or an excessive deterioration of any component related to the idling stop of the engine  16  (hereinafter referred to as “idling stop-related component”). Details of step S 22  will be described later with reference to  FIG. 7 . 
         [0080]    In step S 23 , the engine ECU  20  judges whether the engine  16  is permitted to stop idling or not based on the judgment results from steps S 21 , S 22 . Specifically, if the IS precondition and the IS permitting conditions are satisfied, then the engine ECU  20  judges that the engine  16  is permitted to stop idling, and if the IS precondition or the IS permitting conditions is not satisfied, then the engine ECU  20  judges that the engine  16  is not permitted to stop idling. 
         [0081]    If the engine  16  is not permitted to stop idling (S 23 : NO), then the engine ECU  20  ends the processing sequence of the present processing cycle, and starts the processing sequence of a next processing cycle from step S 21 . 
         [0082]    If the engine  16  is permitted to stop idling (S 23 : YES), then the engine ECU  20  carries out the idling stop control process, shutting down the engine  16  in step S 24 . 
         [0083]    In step S 25 , the engine ECU  20  judges a condition for ending the idling stop control process and restarting the engine  16  (hereinafter referred to as “IS ending condition”). The IS ending condition is satisfied when the clutch pedal  62  is depressed, or stated otherwise, the clutch operated amount θcp becomes equal to or greater than a predetermined value (S 7  in  FIG. 3 ), for example. In addition or alternatively, the IS ending condition may be satisfied when another action is taken by the driver, e.g., at least one of the conditions where the brake pedal  60  is released, or stated otherwise, the brake operated amount θbp becomes equal to or smaller than a predetermined value, and where the accelerator pedal  58  is depressed, or stated otherwise, the accelerator operated amount θap becomes equal to or greater than a predetermined value. 
         [0084]    In step S 26 , the engine ECU  20  judges whether or not the engine  16  is to end its idling stop based on the judgment result from step S 25 . Specifically, if the IS ending condition is satisfied, then the engine ECU  20  judges that the engine  16  is to end its idling stop, and if the IS ending condition is not satisfied, then the engine ECU  20  judges that the engine  16  is not to end its idling stop. 
         [0085]    If the engine  16  is not to end its idling stop (S 26 : NO), then control goes back to step S 24 , keeping the engine  16  stopped from idling. If the engine  16  is to end its idling stop (S 26 : YES), then the engine ECU  20  energizes the starter motor  42  to restart the engine  16  in step S 27 . 
       (2-2-2. Judging IS Preconditions) 
       [0086]      FIG. 5  is a flowchart of a process (details of S 21  in  FIG. 4 ) carried out by the engine ECU  20  for judging IS preconditions.  FIG. 6  is a diagram illustrating information that is supplied to the engine ECU  20  for the engine ECU  20  to judge IS preconditions and IS permitting conditions. 
         [0087]    In step S 31  shown in  FIG. 5 , the engine ECU  20  judges whether the shift position Ps is “N” (neutral) or not based on an output signal from the shift position sensor  52 . 
         [0088]    If the shift position Ps is “N” (S 31 : YES), then the engine ECU  20  judges whether the clutch operated amount θcp of the clutch pedal  62  is zero or not, or stated otherwise, whether the clutch pedal  62  is released or not, based on an output signal from the clutch pedal sensor  50  in step S 32 . The engine ECU  20  may use another threshold value than zero insofar as it is effective to judge that the clutch pedal  62  is released. 
         [0089]    If the clutch operated amount θcp is zero (S 32 : YES), then the engine ECU  20  judges whether the accelerator operated amount θap of the accelerator pedal  58  is zero or not, or stated otherwise, whether the accelerator pedal  58  is released or not, based on an output signal from the accelerator pedal sensor  46  in step S 33 . The engine ECU  20  may use another threshold value than zero insofar as it is effective to judge that the accelerator pedal  58  is released. 
         [0090]    If the accelerator operated amount θap is zero (S 33 : YES), then the engine ECU  20  judges whether or not the vehicle speed V is equal to or lower than 2 km/h, or stated otherwise, whether the vehicle speed V is of a value suitable for stopping the engine  16  from idling or not, based on an output signal from the vehicle speed sensor  54  in step S 34 . The engine ECU  20  may use another threshold value than 2 km/h insofar as it is effective to judge whether the vehicle speed V is of a value suitable for stopping the engine  16  from idling or not. 
         [0091]    If the vehicle speed V is equal to or lower than 2 km/h (S 34 : YES), then the engine ECU  20  judges that the IS preconditions are satisfied in step S 35 . According to the present embodiment, as described above, not only all IS preconditions but also all IS permitting conditions need to be satisfied in order to start the idling stop control process. 
         [0092]    If the answer to any one of steps S 31  through S 34  is NO, then the engine ECU  20  judges that the IS preconditions are not satisfied, i.e., the idling stop control process cannot be started, in step S 36 . 
       (2-2-3. Judging IS Permitting Conditions) 
       [0093]      FIG. 7  is a flowchart of a process (details of S 22  in  FIG. 4 ) carried out by the engine ECU  20  for judging IS permitting conditions. In step S 41 , the engine ECU  20  judges whether the engine hood  188  is closed or not based on an output signal from the engine hood sensor  182  or the SRS ECU  36 . 
         [0094]    If the engine hood  188  is closed (S 41 : YES), then the engine ECU  20  judges whether the seatbelt  190  on the driver seat is fastened or not based on an output signal from the seatbelt sensor  184  or the SRS ECU  36  in step S 42 . 
         [0095]    If the seatbelt  190  is fastened (S 42 : YES), then the engine ECU  20  judges whether the door  192  next to the driver seat is closed or not based on an output signal from the door sensor  186  or the SRS ECU  36  in step S 43 . 
         [0096]    If the door  192  is closed (S 43 : YES), then the engine ECU  20  judges whether the engine  16  has been warmed up or not in step S 44 . Specifically, the engine ECU  20  judges whether or not the engine coolant temperature Tw is equal to or greater than a predetermined value, i.e., a coolant temperature threshold value THtw, and the distance M that the vehicle  12  has traveled after having started is equal to or greater than a predetermined value, i.e., a distance threshold value THm. The engine coolant temperature Tw is represented by an output signal from the coolant temperature sensor  44 , and the traveled distance M is acquired from the meter ECU  32 . 
         [0097]    If the engine  16  has been warmed up (S 44 : YES), then the engine ECU  20  judges whether the brake negative pressure Pn is sufficient or not in step S 45 . Specifically, the engine ECU  20  judges whether or not the brake negative pressure Pn is equal to or greater than a predetermined value, i.e., a negative pressure threshold value THpn, based on an output signal from the negative pressure sensor  80 . Since the brake negative pressure Pn is processed as a positive value, as described above, the greater the brake negative pressure Pn, the more effective it is to brake the vehicle  12 . 
         [0098]    If the brake negative pressure Pn is sufficient (S 45 : YES), then the engine ECU  20  judges whether the VSA function and the ABS function are shut down or not, thereby judging whether the vehicle  12  is under posture control or not, in step S 46 . The engine ECU  20  uses output signals from the VSA ECU  22  and the ABS ECU  24  for the judgment. 
         [0099]    If the VSA function and the ABS function are shut down (S 46 : YES), then the engine ECU  20  judges whether the air conditioner  180  requires no excessively large electric power or not in step S 47 . Specifically, while the air conditioner  180  is in operation, the engine ECU  20  judges whether an outside air temperature Tout falls within a predetermined range or not. 
         [0100]    The predetermined range refers to a range for judging whether the outside air temperature Tout is not an extremely low temperature or an extremely high temperature. Stated otherwise, if the outside air temperature Tout does not fall within the predetermined range, then the load on the air conditioner  180  is necessarily large because it is cold or hot outside the vehicle  12 , requiring the engine  16  to operate the alternator  40 . The outside air temperature Tout is represented by an output signal from an outside air temperature sensor  196  ( FIG. 1 ). 
         [0101]    If the air conditioner  180  requires no excessively large electric power (S 47 : YES), then the engine ECU  20  judges whether or not the vehicle  12  is not being steered, thereby confirming that the vehicle  12  is not in a steered posture intending to start immediately while being stopped at an intersection or the like, in step S 48 . The engine ECU  20  uses an output signal (steering angle θst) from the steering angle sensor  82 . 
         [0102]    If the vehicle  12  is not being steered (S 48 : YES), then the engine ECU  20  judges whether the IS off SW  56  is turned off or not in step S 49 . As described above, if the IS off SW  56  is turned on, the idling stop control function in the engine ECU  20  is inactivated. 
         [0103]    If the IS off SW  56  is turned off (S 49 : YES), then the engine ECU  20  judges whether the remaining energy level (SOC: State Of Charge) of the 12 V battery  86  is sufficient or not in step S 50 . Specifically, the engine ECU  20  judges whether or not the SOC acquired from the battery ECU  30  is equal to or greater than a predetermined threshold value (hereinafter referred to as “first battery threshold value THsoc” or “threshold value THsoc”). 
         [0104]    The SOC is calculated by multiplying the remaining energy level at present divided by the fully charged energy level by 100 {SOC=(remaining energy level at present/fully charged energy level)×100}. The engine ECU  20  can judge in step S 50  whether the voltage drop that occurs across the 12 V battery  86  when the starter motor  42  is energized is lower than a predetermined value or not. If the SOC is equal to or higher than the threshold value THsoc (S 50 : YES), then the need for the engine  16  to operate the alternator  40  to charge the 12 V battery  86  is low. 
         [0105]    If the SOC of the 12 V battery  86  is sufficient (S 50 : YES), then the engine ECU  20  judges whether or not the number Ns of times that the starter motor  42  has been activated, i.e., an activation count Ns, is equal to or smaller than a predetermined value in step S 51 . Specifically, the engine ECU  20  judges whether or not the activation count Ns of the starter motor  42  is equal to or smaller than a predetermined threshold value (hereinafter referred to as “activation count threshold value THns” or “threshold value THns”). The threshold value THns is a value for judging whether the activation count Ns is excessive for the starter motor  42  and the starter motor  42  needs to be replaced or not. If the activation count Ns is equal to or smaller than the threshold value THns (S 51 : YES), then there is no need to avoid the idling stop in view of a deterioration of the starter motor  42 . The activation count Ns of the starter motor  42  is counted by the engine ECU  20  and stored in the memory  74  ( FIG. 6 ). 
         [0106]    If the activation count Ns of the starter motor  42  is equal to or smaller than the predetermined value, i.e., the threshold value THns (S 51 : YES), then the engine ECU  20  judges whether a fault that inhibits an idling stop has occurred or not in step S 52 . Specifically, the engine ECU  20  communicates with each of the ECUs that control respective target ranges including components which may possibly suffer faults that inhibit an idling stop (hereinafter referred to as “IS inhibiting faults”), and confirms whether an IS inhibiting fault has occurred in the target range controlled by any of the ECUs or not. 
         [0107]    If a fault, which may be an IS inhibiting fault or another fault, has occurred in the target range controlled by each ECU, then the ECU stores a fault code in its own memory, e.g., the engine ECU  20  stores a fault code in the memory  74 . The fault code will be used when a fault diagnosis is performed by the external diagnosing apparatus  14  as described in detail later. 
         [0108]    According to the present embodiment, the fault codes include IS fault codes and fault codes that are not defined as inhibiting an idle stop (hereinafter referred to as “non-IS fault code”). The IS fault codes include IS fault codes (hereinafter referred to as “first IS fault codes”) corresponding to relatively serious faults that result in the lighting of warning lamps assigned to the individual ECUs, e.g., the PGM-FI warning lamp  120 , the charging warning lamp  122 , etc. shown in  FIG. 2 , and IS fault codes (hereinafter referred to as “second IS fault codes”) corresponding to relatively minor faults that result in the lighting of only the common indicator lamp  112 , not the warning lamps assigned to the individual ECUs. 
         [0109]    The non-IS fault codes correspond to relatively minor faults that do not result in the lighting of the warning lamps and the indicator lamps. The non-IS fault codes are read and used in fault diagnoses by the external diagnosing apparatus  14  that is connected to the vehicle  12 . 
         [0110]      FIG. 8  is a diagram showing examples of faults corresponding to first IS fault codes, second IS fault codes, and non-IS fault codes. As shown in  FIG. 8 , even if one faulty component, e.g., the 12 V battery  86 , is involved, a fault corresponding to a first IS fault code, e.g., a fault code CCCC in  FIG. 8 : a fault of the alternator  40 , causes the charging warning lamp  122  ( FIG. 2 ) to be lighted, and a fault corresponding to a second IS fault code, e.g., a fault code FFFF in  FIG. 8 : a fault of a battery voltage sensor, causes the IS indicator lamp  112  to be lighted. If the engine  16  is a faulty component, then a fault corresponding to a first IS fault code, e.g., a fault code AAAA in  FIG. 8 : a high engine coolant temperature Tw, causes the PGM-FI warning lamp  120  to be lighted, and a fault corresponding to a second IS fault code, e.g., a fault code EEEE in  FIG. 8 : a high detected sensor voltage, causes the IS indicator lamp  112  to be lighted. 
         [0111]    Faults corresponding to the non-IS fault codes do not cause either the warning lamps or the indicator lamps to be lighted. 
         [0112]    According to the present embodiment, when each ECU detects a fault in a target range controlled by itself, it records the fault code in its own memory, e.g., the engine ECU  20  records the fault code in the memory  74 . 
         [0113]    According to the present embodiment, the engine ECU  20 , the VSA ECU  22 , the ABS ECU  24 , the brake negative pressure ECU  26 , the EPS ECU  28 , the battery ECU  30 , the meter ECU  32 , the air conditioner ECU  34 , and the SRS ECU are established as ECUs that possibly record IS fault codes. The immobilizer ECU  38 , however, is not established as an ECU that possibly records IS fault codes. 
         [0114]    Referring back to step S 52  in  FIG. 7 , if a fault that inhibits an idling stop has not occurred (S 52 : YES), then the engine ECU  20  judges that the IS permitting conditions are satisfied in step S 53 . According to the present embodiment, as described above, it is necessary to satisfy not only all IS permitting conditions but also all IS preconditions in order to start the idling stop control process. 
         [0115]    If even any one of the answers to steps S 41  through S 52  is NO, then the engine ECU  20  judges that the IS permitting conditions are not satisfied, i.e., the idling stop control process cannot be started, in step S 54 . 
       (2-3. Idling Stop-related Display Control Process Carried out by the Engine ECU  20 ) 
     (2-3-1. Overall Flow) 
       [0116]    A process carried out by the engine ECU  20  to change displayed information on the meter display device  92  through the meter ECU  32 , i.e., an idling stop-related display control process, during the processing sequence shown in  FIG. 3 , will be described below. 
         [0117]      FIGS. 9 and 10  are first and second flowcharts, respectively, of an idling stop-related display control process carried out by the engine ECU  20 . In step S 61  shown in  FIG. 9 , the engine ECU  20  judges whether the above idling stop (IS) preconditions (see  FIG. 5 ) are satisfied or not. If the IS preconditions are satisfied (S 61 : YES), then the engine ECU  20  judges whether the above idling stop (IS) permitting conditions (see  FIG. 7 ) are satisfied or not in step S 62 . 
         [0118]    If the IS permitting conditions are satisfied (S 62 : YES), then the engine  16  is normally stopped from idling. In step S 63 , the engine ECU  20  controls the meter ECU  32  to light the IS indicator lamp  112  ( FIG. 2 ) in green in order to indicate to the driver that the engine  16  is stopped from idling. Other information may be displayed insofar as it indicates to the driver that the engine  16  is stopped from idling. 
         [0119]    In step S 62 , if the IS permitting conditions are not satisfied (S 62 : NO), then the engine ECU  20  judges whether the VSA function and the ABS function are shut down or not, thereby judging whether the vehicle  12  is under posture control or not, in step S 64 . 
         [0120]    If the VSA function and the ABS function are shut down (S 64 : YES), then the engine ECU  20  judges whether the vehicle  12  is not being steered, thereby confirming that the vehicle  12  is not in a steered posture intending to start immediately while being stopped at an intersection or the like, in step S 65 . 
         [0121]    If the vehicle  12  is not being steered (S 65 : YES), then the engine ECU  20  judges whether the IS off SW  56  is turned off or not in step S 66 . 
         [0122]    If the IS preconditions are not satisfied (S 61 : NO), the VSA function and the ABS function are not shut down (S 64 : NO), the vehicle  12  is being steered (S 65 : NO), or the IS off SW  56  is not turned off (S 66 : NO), then the engine ECU  20  controls the meter ECU  32  to de-energize the IS indicator lamp  112  in step S 67 . If the IS off SW  56  is turned off (S 66 : YES), then control goes to step S 68  in  FIG. 10 . 
         [0123]    In step S 68  in  FIG. 10 , the engine ECU  20  judges whether a deteriorated state (SOH: State Of Health) of the 12 V battery  86  is good or not. Specifically, the engine ECU  20  judges whether or not the SOH acquired from the battery ECU  30  is equal to or greater than a predetermined threshold value (hereinafter referred to as “second battery threshold value THsoh” or “threshold value THsoh”). 
         [0124]    The SOH is calculated by multiplying the fully charged energy level at present divided by the initial fully charged energy level by 100 {SOH=(fully charged energy level at present/initial fully charged energy level)×100}. The engine ECU  20  can judge in step S 68  whether the voltage drop that occurs across the 12 V battery  86  when the starter motor  42  is energized is lower than a predetermined value or not. 
         [0125]    The judgment results from steps S 51 , S 52 , S 47  in  FIG. 7  may directly be used as judgment results in steps S 69 , S 70 , S 72  in  FIG. 10 . 
         [0126]    If the SOH of the battery  86  is good in step S 68  (S 68 : YES), then the engine ECU  20  judges whether or not the activation count Ns of the starter motor  42  is equal to or smaller than a predetermined value, i.e., the threshold value THns, in step S 69 . If the activation count Ns of the starter motor  42  is equal to or smaller than the predetermined value (S 69 : YES), then the engine ECU  20  judges whether a fault that inhibits an idling stop has occurred or not in step S 70 . 
         [0127]    If the SOH of the battery  86  is not good (S 68 : NO), the activation count Ns of the starter motor  42  is not equal to or smaller than the predetermined value (S 69 : NO), or a fault that inhibits an idling stop has occurred (S 70 : NO), then the engine ECU  20  controls the meter ECU  32  to light the IS indicator lamp  112  in red in order to indicate to the driver that the engine  16  is not stopped from idling in step S 71 . 
         [0128]    According to the present embodiment, after the IS indicator lamp  112  has been lighted in red, it is continuously lighted in red until the cause is removed, i.e., until the fault corresponding to the stored fault code is eliminated by repairing. Consequently, even if the IS preconditions have come to be not satisfied, the IS indicator lamp  112  is continuously lighted in red. 
         [0129]    If a fault that inhibits an idling stop has occurred (S 70 : NO), then the IS indicator lamp  112  is lighted in red only upon occurrence of a fault recording an IS fault code (second IS fault code) that does not display a warning lamp, e.g., the PGM-FI warning lamp  120 , the charging warning lamp  122 , or the like, corresponding to a specific ECU, and the IS indicator lamp  112  is de-energized upon occurrence of a fault which records an IS fault code (first IS fault code) that lights a warning lamp corresponding to a specific ECU. However, according to another process, the IS indicator lamp  112  may simultaneously be lighted when a fault recording a first IS fault code has occurred. 
         [0130]    If a fault that inhibits an idling stop has not occurred in step S 70  (S 70 : YES), then the engine ECU  20  judges whether the air conditioner  180  requires no excessively large electric power or not in step S 72 . If the air conditioner  180  requires no excessively large electric power (S 72 : YES), then the engine ECU  20  controls the meter ECU  32  to de-energize the IS indicator lamp  112  in step S 73 . If the air conditioner  180  requires excessively large electric power (S 72 : NO), then the engine ECU  20  controls the meter ECU  32  to blink the IS indicator lamp  112  in green in order to indicate to the driver that the air conditioner  180  requires excessively large electric power in step S 74 . Other information may be displayed insofar as it indicates to the driver that the air conditioner  180  requires excessively large electric power. 
         [0131]    For an easier understanding of the present embodiment, the idling stop control process carried out by the engine ECU  20  ( FIG. 4 ) and the idling stop-related display control process carried out by the engine ECU  20  ( FIGS. 9 and 10 ) have been described separately. However, the idling stop control process shown in  FIG. 4  and idling stop-related display control process shown in  FIGS. 9 and 10  include many common steps, e.g., steps of judging whether a IS precondition is satisfied or not (S 21  in  FIG. 4 , S 61  in  FIG. 9 ). Therefore, the idling stop control process and the idling stop-related display control process may be combined into a control process. 
         [0132]    The idling stop-related display control process ( FIGS. 9 and 10 ) has been described as being mainly carried out by the engine ECU  20 . However, judgment steps shown in  FIGS. 9 and 10  may be carried out by the meter ECU  32  either uniquely or using output signals from the engine ECU  20 . If the meter ECU  32  uses output signals from the engine ECU  20 , then the meter ECU  32  may judge whether it has received a signal indicating that the engine  16  is being stopped from idling from the engine ECU  20 , rather than performing steps S 61 , S 62 . 
       [3. Vehicle Diagnosing Process] 
     (3-1. Operating Sequence of the Operator) 
       [0133]      FIG. 11  is a flowchart of a sequence followed when a fault diagnosis is performed on the vehicle  12  using the external diagnosing apparatus  14 . The flowchart shown in  FIG. 11  represents a diagnostic sequence followed by the operator when the user of the vehicle  12  has reported that the IS indicator lamp  112  is lighted in red or when the user of the vehicle  12  has reported that the engine  16  often fails to be stopped from idling. If the vehicle  12  suffers a fault that causes a warning lamp, e.g., the PGM-FI warning lamp  120 , the charging warning lamp  122 , or the like shown in  FIG. 2 , corresponding to a specific ECU, to be lighted (see  FIG. 8 ), then the operator can identify an ECU based on the lighted warning lamp and proceed with a diagnosis for identifying the cause of the fault. 
         [0134]    In step S 101 , the operator turns on the ignition switch, not shown, and judges whether the IS indicator lamp  112  on the meter display device  92  is turned on in red or not {at this time, the vehicle  12  (the engine  16 ) is stopping}. 
         [0135]    If the IS indicator lamp  112  is lighted in red (S 101 : YES), then the operator connects the external diagnosing apparatus  14  to the data link connector  194  of the vehicle  12 , and reads the fault codes recorded in the ECUs through the external diagnosing apparatus  14 , thereby performing a troubleshooting process using the external diagnosing apparatus  14  in step S 102 . 
         [0136]      FIG. 12  shows by way of example a screen displayed when the external diagnosing apparatus  14  has diagnosed the conditions of various components of the vehicle  12  by reading out fault codes recorded in the ECUs of the vehicle  12  while the IS indicator lamp  112  is being lighted in red. Details of  FIG. 12  will be described later with reference to  FIG. 14 . The operator can inspect or repair the vehicle  12  while seeing the displayed screen shown in  FIG. 12 . 
         [0137]    Referring back to step S 101  shown in  FIG. 11 , if the IS indicator lamp  112  is not being lighted in red (S 101 : NO), then the operator judges whether the idling stop control process is normally performed or not while the vehicle  12  is being driven with the operator sitting on the front passenger seat, for example, in step S 103 . Specifically, in a test run, the operator asks the driver to repeat a driving behavior in which the engine  16  often fails to be stopped from idling, and confirms that the engine  16  fails to be stopped from idling when the vehicle  12  comes to a halt. In other words, the operator judges whether the engine  16  is automatically shut down while the IS preconditions are being satisfied, and the IS indicator lamp  112  is lighted in green or not. 
         [0138]    If the idling stop control process is normally performed and its non-execution is not repeated (S 103 : YES), then the operator judges that the idling stop control process is normally performed on the vehicle  12  in step S 104 . As a precautionary measure and in view of the claim made by the user, however, the operator may inspect various components related to the idling stop control process, or may confirm various components of the vehicle  12  using the external diagnosing apparatus  14 , as with the case with step S 105  to be described below. 
         [0139]    If the idling stop control process is not executed (S 103 : NO), then the operator performs a troubleshooting process using the external diagnosing apparatus  14  in step S 105 . 
         [0140]    Specifically, as with step S 102 , the operator connects the external diagnosing apparatus  14  to the vehicle  12  to establish communication between the external diagnosing apparatus  14  and the ECUs of the vehicle  12 . Then, the operator operates the operating unit  204  of the external diagnosing apparatus  14  to start a diagnosis about the idling stop control process. Thereafter, the operator drives the vehicle  12  to satisfy the IS preconditions. 
         [0141]    Specifically, in a test run as described above, the operator asks the driver to repeat a driving behavior in which the engine  16  often fails to be stopped from idling, attempting to replicate the state that the engine fails to be stopped from idling when the vehicle  12  comes to a halt. 
         [0142]    The display unit  210  of the external diagnosing apparatus  14  then displays a screen shown in  FIG. 13 . For example, details of the displayed screen shown in  FIG. 13  will be described later with reference to  FIG. 15 . The operator is now able to analyze reasons why the engine  16  of the vehicle  12  fails to be stopped from idling while seeing the displayed screen shown in  FIG. 13 . 
         [0143]    The operator can then explain to the user the way in which the vehicle  12  is driven with the idling stop control process being not executed, using the displayed screen shown in  FIG. 13 . For example, if the engine  16  is displayed as being warmed up (S 44  in  FIG. 7 ), then the operator judges that the engine  16  has not been warmed up and tells the user the fact that the engine  16  has not been warmed up. If the brake negative pressure Pn is displayed as not being sufficient (S 45  in  FIG. 7 ), then the operator can point out that the user has done brake pumping excessively. 
       (3-2. Processing Sequence of the External Diagnosing Apparatus  14 ) 
     (3-2-1. If the IS Indicator Lamp  112  is Lighted in Red) 
       [0144]      FIG. 14  is a flowchart of a processing sequence carried out by the external diagnosing apparatus  14  for confirming the states of the various components of the vehicle  12  if the IS indicator lamp  112  is lighted in red. As described above, if the vehicle  12  suffers a fault that causes a warning lamp, e.g., the PGM-FI warning lamp  120 , the charging warning lamp  122 , or the like shown in  FIG. 2 , corresponding to a specific ECU, to be lighted, then the operator can identify an ECU based on the lighted warning lamp and proceed with a diagnosis for identifying the cause of the fault. Stated otherwise, the external diagnosing apparatus  14  separately carries out a diagnostic process at the time such a warning lamp is lighted (hereinafter referred to as “specific warning lamp-lighted diagnostic process”and a diagnostic process at the time the idling stop is not executed though a warning lamp corresponding to a specific ECU is not lighted (hereinafter referred to as “IS diagnostic process”). The processing sequence shown in  FIG. 14  represents the IS diagnostic process. 
         [0145]    In step S 111 , the external diagnosing apparatus  14  judges whether the operator has made a request for the confirmation of the situations of various components of the vehicle  12  (hereinafter referred to as “first IS system test”) or not while the IS indicator lamp  112  is being lighted in red. If there is no request for the first IS system test (S 111 : NO), then the present cycle of the processing sequence is ended. 
         [0146]    If there is a request for the first IS system test (S 111 : YES), then in step S 112  the external diagnosing apparatus  14  communicates with the ECUs to inquire whether there is a cause of the red lighting of the IS indicator lamp  112 , e.g., a recorded second IS fault code, or not, and, in the event that there is such a cause, acquires data related to an IS precondition (see  FIG. 5 ) and an IS permitting condition (see  FIG. 7 ) at the time the cause occurs. At this time, the external diagnosing apparatus  14  may communicate with only an ECU that is possibly recording the cause, e.g., an ECU that is possibly recording a second IS fault code. 
         [0147]    The action performed by the external diagnosing apparatus  14  to make the rounds of the ECUs to communicate therewith is referred to as “round access”. Instead of performing a round access, the external diagnosing apparatus  14  may acquire judgment results from the engine ECU  20 , etc. 
         [0148]    As described above, the external diagnosing apparatus  14  according to the present embodiment separately carries out a diagnostic process at the time a warning lamp assigned to an individual ECU, e.g., the PGM-FI warning lamp  120 , the charging warning lamp  122 , or the like, is lighted (specific warning lamp-lighted diagnostic process) and a diagnostic process at the time the idling stop is not executed though the warning lamp is not lighted (IS diagnostic process). An IS fault code that the external diagnosing apparatus  14  inquires about its presence or not in step S 112  corresponds to a fault that does not light a warning lamp, i.e., a second IS fault code (see  FIG. 8 ). Stated otherwise, in step S 112 , the external diagnosing apparatus  14  does not inquire each ECU whether there is a first IS fault code or not. In this manner, the external diagnosing apparatus  14  has its processing load reduced and its processing time shortened. 
         [0149]    In step S 113 , the external diagnosing apparatus  14  displays the judgment result of step S 112  on the display unit  210  (see  FIG. 12 ). 
         [0150]    As shown in  FIG. 12 , the judgment result or screen displayed in step S 113  displays whether a fault has occurred or not with respect to each of the causes that can light the IS indicator lamp  112  in red. Specifically, the displayed screen shown in  FIG. 12  displays whether the SOH of the battery  86  is sufficient or not (S 68  in  FIG. 10 ), whether or not the activation count Ns of the starter motor is equal to or smaller than the predetermined value (S 69 ), and whether there are second IS fault codes or not (S 70 ). 
         [0151]    As shown in  FIG. 12 , the display unit  210  displays whether there are recorded second IS fault codes or not and, if there are recorded second IS fault codes, details thereof, with respect to the respective ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded. 
         [0152]    Therefore, it is possible to display whether there are recorded second IS fault codes or not and, if there are recorded second IS fault codes, details thereof, with respect to the respective ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded. The displayed screen shown in  FIG. 12  thus makes it easy for the operator to judge and verify the results of the inquiries made by the external diagnosing apparatus  14 . 
       (3-2-2. If the IS Indicator Lamp  112  is Not Lighted in Red) 
       [0153]      FIG. 15  is a flowchart of a processing sequence carried out by the external diagnosing apparatus  14  for confirming the states of the various components of the vehicle  12  if the IS indicator lamp  112  is not lighted in red. 
         [0154]    In step S 121 , the external diagnosing apparatus  14  judges whether the operator has made a request for the confirmation of the situations of various components of the vehicle  12  (hereinafter referred to as “second IS system test”) or not while the IS indicator lamp  112  is not being lighted in red. If there is no request for the second IS system test (S 121 : NO), then the present cycle of the processing sequence is ended. 
         [0155]    If there is a request for the second IS system test (S 121 : YES), then the external diagnosing apparatus  14  judges whether the IS preconditions (see  FIG. 5 ) are satisfied or not by communicating with the engine ECU  20  in step S 122 . At this time, the external diagnosing apparatus  14  may communicate with the engine ECU  20  only for the purpose of acquiring values for judging whether the IS preconditions are satisfied or not. 
         [0156]    If the IS preconditions are satisfied (S 122 : YES), then the external diagnosing apparatus  14  judges whether the IS permitting conditions (see  FIG. 7 ) are satisfied or not by communicating with the engine ECU  20  in step S 123 . At this time, the external diagnosing apparatus  14  may communicate with the engine ECU  20  only for the purpose of acquiring values and states for judging whether the IS permitting conditions are satisfied or not. 
         [0157]    In step S 124 , the external diagnosing apparatus  14  displays the judgment result of step S 123  on the display unit  210  (see  FIG. 13 ). As shown in  FIG. 13 , the displayed judgment result or screen displays that the idling stop is not executed because the SOC of the battery  86  is not equal to or greater than 40%. According to the present embodiment, therefore, the judgment results and current states of the IS preconditions and the IS permitting conditions are displayed, and the details of the IS preconditions and the IS permitting conditions are also displayed. 
         [0158]    The displayed judgment results, current states, and the IS preconditions and the IS permitting conditions allow the operator to judge which one of the IS preconditions and the IS permitting conditions is not satisfied, and also allow the operator to tell the user that the idling stop is not executed because the vehicle  12  is in a situation where the idling stop should not be executed, rather than suffering a fault, as the result of the judgment. For example, if the engine coolant temperature Tw in the item “ENGINE COOLANT TEMPERATURE” is lower than “45° C.” and the engine  16  has not been warmed up, then the operator can point out to the user that the engine  16  has not been warmed up. If the brake negative pressure Pn is lower than “39.1 kPa” in the item “BRAKE NEGATIVE PRESSURE”, then the operator can point out to the user that the user has done brake pumping excessively while driving the vehicle  12 . 
         [0159]    Referring back to step S 122  in  FIG. 15 , if the IS preconditions are not satisfied (S 122 : NO), then the external diagnosing apparatus  14  displays an error message on the display unit  210  in step S 125 . 
       [4. Advantages of the Embodiment] 
       [0160]    According to the present embodiment, as described above, the vehicle  12  includes the IS indicator lamp  112  (idling stop failure indicator). When a fault which records the second IS fault code (see  FIG. 8 ) is occurred in any of ECUs, the IS indicator lamp  112  indicates that the fault corresponding to the second IS fault code has occurred. The fault which records the second IS fault code does not light or blink the warning lamp  104  or the like. When the fault that does not light or blink the warning lamp  104  or the like but inhibits an idling stop from occurring, the driver can recognize the occurrence of the fault based on the indication of the IS indicator lamp  112 . 
         [0161]    Accordingly, even if an idling stop is not executed in a case where the driver of the vehicle tends to expect that the idling stop is carried out, e.g., when the driver waits for the traffic light at an intersection, the driver can simply and visually confirm the indication of the idling stop failure indicator to see if the reason for the non-execution of the idling stop is due to the fault corresponding to the first IS fault mode or the second IS fault mode. Therefore, the driver can concentrate on driving securely without having an unnecessary sense of mistrust such that the idling stop is not executed properly. 
         [0162]    The second IS fault codes correspond to minor faults compared to the first IS fault codes. By utilizing both of the warning lamp  104  or the like and the IS indicator lamp  112 , the driver can recognize the degree of urgency about the fault case by case. In a repair shop or the like for a fault diagnosis of the vehicle  12 , the second IS fault codes can also be used as a guide for performing diagnoses on the ECUs. 
         [0163]    In the present embodiment, when the faults that record the second IS fault codes in any of the ECUs have occurred in target ranges controlled thereby, the single IS indicator lamp  112  is used for indicating that the faults (idling stop faults) corresponding to the second IS fault codes have occurred (S 70  in  FIG. 10 : NO→S 71 ). 
         [0164]    Generally, each of warning lamps in the vehicle which demands an inspection or repair of a failure in the vehicle is associated with a specific ECU. Stated otherwise, when an energized (lighted, blinked or the like) warning lamp is specified, the ECU for controlling the failure component can be identified. In contrast, when faults which record the second IS fault codes in any of the ECUs have occurred in target ranges controlled thereby, the single IS indicator lamp  112  is used for indicating that the idling stop faults have occurred. Thus, only one IS indicator lamp  112  indicates that the idling stop faults have occurred when any of the ECUs detect the idling stop faults. Accordingly, the user can easily recognize whether an idling stop failure has occurred or not while the user is driving the vehicle. 
         [0165]    In the present embodiment, regardless of a fact that the fault which records the one of the second IS codes in any of the ECUs has occurred in a target range controlled thereby, the idling stop is inhibited and the idling stop fault is indicated (i.e., the IS indicator lamp  112  is lighted in red) when the activation count Ns of the starter motor  42  is larger than a predetermined value (activation count threshold value THns) (S 69  in  FIG. 10 : NO) or when the voltage drop across the 12 V battery  86  at the time the starter motor  42  is energized is lower than a predetermined value (S 68  in  FIG. 10 : NO). 
         [0166]    Even if no fault has occurred in the vehicle  12 , the driver can recognize a risk that the vehicle cannot possibly be started owing to the deterioration or the like, through the indication of the IS indicator lamp  112 . 
       B. Modifications 
       [0167]    The present invention is not limited to the above embodiment, but may employ various arrangements based on the disclosure of the description thereof. For example, the present invention may employ the following arrangements: 
       [1. Objects Incorporating the Invention] 
       [0168]    In the above embodiment, the external diagnosing apparatus  14  is incorporated in the vehicle  12 . However, the external diagnosing apparatus  14  may be incorporated in other apparatus, e.g., mobile objects including ships, aircrafts, etc. whose drive source may be stopped from idling. The drive source may not necessarily be a drive source for generating drive power for directly moving a mobile object such as the vehicle  12  or the like, but may be an engine for actuating a motor to generate electric power on the vehicle  12 . Alternatively, the drive source may be a drive force generator such as a cooling pump, an air compressor, or the like for use in a mobile object such as the vehicle  12  or a manufacturing apparatus. 
       [2. Vehicle  12 ] 
     (2-1. Arrangement) 
       [0169]    In the above embodiment, the vehicle  12  is an MT vehicle. However, the vehicle  12  is not limited to an MT vehicle, but may be other vehicles insofar as their drive source can be stopped from idling, such as an automatic transmission vehicle (AT vehicle), for example. 
         [0170]    In the above embodiment, the vehicle  12  is a diesel-powered vehicle. However, the vehicle  12  is not limited to a diesel-powered vehicle, but may be other vehicles insofar as their drive source can be stopped from idling, such as a gasoline-powered vehicle, a hybrid vehicle, or a fuel cell vehicle. 
       (2-2. Conditions for an Idling Stop) 
       [0171]    In the above embodiment, the conditions for use in the idling stop control process ( FIG. 4 ) are separated into the IS preconditions ( FIG. 5 ) and the IS permitting conditions ( FIG. 7 ). However, the conditions for use in the idling stop control process may not necessarily be divided into the IS preconditions and the IS permitting conditions. Specifically, since it is sufficient for those conditions to judge whether an idling stop is to be executed or not according to the idling stop control process, unlike the idling stop-related display control process ( FIGS. 9 and 10 ), the IS preconditions and the IS permitting conditions may be used together as idling stop (IS) conditions. 
         [0172]    According to the idling stop-related display control process, if the driver can be notified of a state wherein an idling stop cannot be executed though the IS preconditions are satisfied, then the processing sequences according to the flowcharts shown in  FIGS. 9 and 10 , i.e., the processing sequences for separately carrying out the steps of judging the IS preconditions and the steps of judging the IS permitting conditions, may not have to be carried out, but operation of the IS indicator lamp  112  may be determined based on a combination of conditions related to an idling stop. 
         [0173]    The details of the IS preconditions and the IS permitting conditions for use respectively in the idling stop control process and the idling stop-related display control process may be changed appropriately providing that the IS preconditions include at least one precondition for an idling stop. The one precondition includes a condition that can be recognized by the driver for driving the vehicle  12 . 
         [0174]    Stated otherwise, a situation in which the driver assumes that the execution of an idling stop may be established as an IS precondition and the IS indicator lamp  112  or the like may indicate that an idling stop is not executed though the IS precondition is satisfied. For example, providing that the IS preconditions include at least one precondition for an idling stop which can be recognized by the driver for driving the vehicle  12 , it is possible to establish any conditions included in the IS permitting conditions according to the above embodiment as IS preconditions, and also to establish any conditions included in the IS preconditions according to the above embodiment as IS permitting conditions. 
         [0175]    The term “IS permitting conditions” is essentially the same as the term “idling stop (IS) prohibiting conditions” except that satisfying the IS permitting conditions means not satisfying the IS prohibiting conditions. 
       (2-3. Lighting/Blinking of the IS Indicator Lamp  112 ) 
       [0176]    In the above embodiment, the IS indicator lamp  112  (idling stop failure indicator) is lighted or blinks in green when an idling stop is executed (S 63  in  FIGS. 9  and S 74  in  FIG. 10 ), and in red when the idling stop permitting conditions are partly not satisfied (S 71  in  FIG. 10 ). However, the IS indicator lamp  112  may be operated otherwise insofar as it allows the driver to judge when an idling stop is executed, when an idling step is not executed though the IS preconditions are satisfied, and when the IS preconditions are not satisfied. 
         [0177]    For example, the IS indicator lamp  112  may be lighted in green when an idling stop is executed, in red in S 71  in  FIG. 10 , in yellow when the other IS permitting conditions are not satisfied, and may be de-energized when the IS preconditions are not satisfied. 
         [0178]    In the above embodiment, if a second IS fault code is recorded in any of the ECUs, the IS indicator lamp  112  is lighted in red (S 70  in  FIG. 10 : NO→S 71 ). However, a plurality of IS indicator lamps  112  may be provided, and a different IS indicator lamp  112  may be lighted or blink for each of the ECUs. 
         [0179]    In the above embodiment, the IS indicator lamp  112  is used to indicate the non-execution of an idling stop when a second IS fault code is recorded. However, the non-execution of an idling stop may be indicated differently, e.g., on the fifth display unit  102  (MID). 
       [3. External Diagnosing Apparatus  14 ] 
     (3-1. Arrangement) 
       [0180]    In the above embodiment, the external diagnosing apparatus  14  may be a single unit comprising a laptop personal computer, a tablet computer, or a smart phone that is commercially available, for example. However, the external diagnosing apparatus  14  may be a combination of a personal computer as a main unit and a slave unit (tester) as an interface with the vehicle  12 . 
         [0181]    In the above embodiment, the external diagnosing apparatus  14  communicates with each of the ECUs through the communication cable  200 . However, the external diagnosing apparatus  14  may communicate with each of the ECUs through a wireless link. 
         [0182]    The diagnostic software used by the external diagnosing apparatus  14  is prerecorded in the memory  208 . However, the diagnostic software may be downloaded from an external source, e.g., an external server that can be accessed through a public network, or may be executed using a download-free ASP (Application Service Provider). 
       (3-2. Control) 
       [0183]    In the flowchart shown in  FIG. 14 , the external diagnosing apparatus  14  requests the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded to send only second IS fault codes. However, the external diagnosing apparatus  14  may request the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  to send data insofar as they include second IS fault codes. For example, the external diagnosing apparatus  14  may request the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  to send first IS fault codes and second IS fault codes, and then the second IS fault codes may be extracted on the side of the external diagnosing apparatus  14 . Alternatively, the external diagnosing apparatus  14  may request the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  to send all fault codes (first IS fault codes, second IS fault codes, and non-IS fault codes) or second IS fault codes and non-IS fault codes, and then the second IS fault codes may be extracted on the side of the external diagnosing apparatus  14 . 
         [0184]    If fault codes other than second IS fault codes are sent, they may be processed as follows: The external diagnosing apparatus  14  may have a database included in the memory  208 , the database having registered second IS fault codes corresponding to the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded, or may download such a database from an external source. 
         [0185]    Then, the external diagnosing apparatus  14  reads out second IS fault codes and other fault codes from the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded. The external diagnosing apparatus  14  may then compare the read fault codes with the fault codes registered in the database in association with the ECUs  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 ,  34 ,  36  which may possibly have second IS fault codes recorded, and extract second IS fault codes. 
         [0186]    Consequently, even though the fault codes read by the external diagnosing apparatus  14  include fault codes other than second IS fault codes, the external diagnosing apparatus  14  can simply extract second IS fault codes. 
       (3-3. Displayed Screens) 
       [0187]    In the above embodiment, the diagnostic result from the external diagnosing apparatus  14  is displayed on the display unit  210  thereof. However, the diagnostic result from the external diagnosing apparatus  14  may be displayed on a monitor, not shown, of a navigation device, not shown, on the vehicle  12 . 
         [0188]    In the above embodiment, the screens shown in  FIGS. 12 and 13  are displayed on the display unit  210 . However, screens for displaying diagnostic results are not limited to those illustrated screens. 
         [0189]    For example, in  FIGS. 12 and 13 , the details of the IS permitting conditions that are satisfied are displayed in addition to the details of the IS permitting conditions that are not satisfied. However, only the details of the IS permitting conditions that are not satisfied may be displayed. 
         [0190]    According to the flowchart shown in  FIG. 15 , the screen ( FIG. 13 ) is displayed only if the IS preconditions are satisfied (S 122 : YES→S 124  in  FIG. 15 ). However, even if the IS preconditions are not satisfied, a screen with respect to at least one of the IS preconditions and the IS permitting conditions may be displayed. In this case, it is preferable to display on the screen information about whether the IS preconditions are satisfied or not.