ON-BOARD DIAGNOSTIC SYSTEM 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
	WDS or equivalent	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
	B1318	Illuminated	Not illuminated^*2	Not available	Available^*2
ABS 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	C1446	Not illuminated	Not illuminated	Available	Available
CAN communication	U2012	Not illuminated^*5	Not illuminated^*5	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.