#
ON-BOARD DIAGNOSTIC FUNCTION

id040200175100

## Malfunction Detection Function

• The malfunction detection function detects malfunctions in the input/output signal system of the ABS HU/CM when the ignition switch is at the ON position.
• When the ABS HU/CM are started up, the following malfunction detections are performed.

  - The ABS and brake system warning lights illuminate for approx. 3.0 s when the ignition switch is turned to the ON position to inspect for open circuits in the lights. At the same time, the fail-safe relay is operated, and the input/output signals of each part is monitored for malfunction diagnosis. After starting to drive, the first time the vehicle speed is approx. 10 km/h {6.2 mph} or more the pump motor is operated and malfunction diagnosis is performed again. Input/output signals are monitored for malfunction determination when the ignition switch is at the ON position.

• When malfunctions are detected, the corresponding lights are illuminated to alert the driver. Using the external tester communication function, DTCs can be output through the KLN of the DLC-2. At the same time, malfunction detection results are sent to the memory and fail-safe functions.

## Memory Function

• The memory function stores DTCs of malfunctions in input/output signal systems. With this function, once a DTC is stored it is not cleared after the ignition switch has been turned off (LOCK position), even if the malfunctioning signal system has returned to normal.
• Since the ABS control modules have built-in non-volatile memory, DTCs are not cleared even if the battery is removed. Therefore, it is necessary to clear the memory after performing repairs. Refer to the Workshop Manual for the DTC clearing procedure.

## Fail-safe Function

• If a failure is detected in the self-diagnostic function, the fail-safe illuminates the ABS warning light and BRAKE system warning light to notify the driver. At the same time, the ABS HU/CM controls the ABS and EBD. The fail-safe function ensures normal braking even when ABS and EBD control stops, as shown in the table.

  Caution

  • In the event that EBD control stops, the rear wheels may lock before the front wheels, causing the vehicle to skid. Inspect the system immediately if EBD control stops.

Fail-safe function table

Malfunction location | DTC | Fail-safe function
--- | --- | ---
WDS or equivalent | Warning light illumination condition | Control condition
ABS warning light | BRAKE system warning light (when parking brake is released) | ABS control | EBD control
Power supply | B1317 | Illuminated | Illuminated | Not available | Not available
B1318 | Illuminated | Illuminated*1 | Not available | Not available*1
Not illuminated*2 | Available*2
ABS HU/CM | B1342 | Illuminated | Illuminated | Not available | Not available
Pump motor, motor relay | C1095 | Illuminated | Not illuminated | Not available | Available
ABS sensor rotor | C1141 | Illuminated | Not illuminated *3 | Not available | Available*4
C1142
C1143
C1144
ABS wheel-speed sensor | C1145 | Illuminated | Not illuminated *3 | Not available | Available*4
C1155
C1165
C1175
ABS wheel-speed sensor/sensor rotor | C1233 | Illuminated | Not illuminated *3 | Not available | Available*4
C1234
C1235
C1236
ABS CM internal failure | C1267 | Illuminated | Illuminated | Not available | Not available
Brake light switch | B1446 | Not illuminated | Not illuminated | Available | Available
CAN communication | U2523 | Not illuminated*5 | Not illuminated*5 | Available | Available

  *1 :
Detected if voltage is 8 V±0.5V or less , regardless of duration.
  *2 :
Detected if voltage remains at 9.7 V±0.3V or less for 210 ms or more .
  *3 :
lluminates if two wheels or more have a malfunction.
  *4 :
Control not available if two wheels or more have a malfunction.
  *5 :
May illuminate depending on malfunction contents.