The ABS warning lamp is controlled by the ABS-ECU. The warning lamp drive circuit in the combination meter contains an reversal circuit, which turns the ABS warning lamp off when the transistor in the ABS-ECU is ON and turns the lamp on when the transistor is OFF. When the system is normal, the ABS-ECU keeps the transistor ON. When it detects a system error, it turns the transistor OFF to turn the ABS warning lamp on. The ABS warning lamp also comes on when the ABS-ECU connector is disconnected.

The ABS-ECU includes the following functions to make system inspection easier.
All of the above operations can be carried out using the MUT-II/III.

• Diagnosis code output

• service data output

• Actuator testing

Diagnosis code No.	Item	Action during fail-safe operation
		ABS control	EBD control	ABS warning lamp
11	Open circuit or short-circuit in ABS sensor (FR)	Control stopped if any faulty wheel detects	If faulty wheels include two rear wheels: Control stopped Other than the above: Control carried out	Illuminated
12	Open circuit or short-circuit in ABS sensor (FL)
13	Open circuit or short-circuit in ABS sensor (RR)
14	Open circuit or short-circuit in ABS sensor (RL)
16	Abnormal drop or rise in ABS-ECU power supply voltage	Control stopped	Control stopped (when high voltage) Control carried out (when low voltage)	Illuminated
21	ABS sensor (FR) system	If any faulty wheel detects: Control stopped in all wheels	If faulty wheels include two rear wheels: Control stopped Other than the above: Control carried out	Illuminated
22	ABS sensor (FL) system
23	ABS sensor (RR) system
24	ABS sensor (RL) system
32	G sensor system <4WD>	Control stopped	Control carried out	Illuminated
41	Solenoid valve (FR) system	System interrupted	System interrupted	Illuminated
42	Solenoid valve (FL) system
43	Solenoid valve (RR) system
44	Solenoid valve (RL) system
51	Valve relay ON problem	Control stopped	Control carried out	Illuminated
52	Valve relay OFF problem	System interrupted	System interrupted	Illuminated
53	Motor relay OFF problem	Control stopped	Control carried out	Illuminated
54	Motor relay ON problem	System interrupted	Control carried out	Illuminated
55	Motor system	Control stopped	Control carried out	Illuminated
63	ABS-ECU abnormality	System interrupted	System interrupted	Illuminated

The diagnosis codes can be checked using the MUT-II/III, and also by the flashing of the ABS warning lamp. (Refer to Service Manual.)

The diagnosis codes can be cleared using the MUT-II/III or by special operation for the brake pedal. (Refer to Service Manual.)

The data input from all sensors and switches can be read using the MUT-II/III.

Item No.	Check item	Checking requirement	Normal value
11	Front-right ABS sensor	Drive the vehicle	Vehicle speeds displayed on the speedometer and MUT-II/III are identical.
12	Front-left ABS sensor
13	Rear-right ABS sensor
14	Rear-left ABS sensor
21	ABS-ECU power supply voltage	Ignition switch power supply voltage and valve monitor voltage	10 - 16 V
32	G-sensor <4WD>	Ignition switch: ON When vehicle is parked on a level surface.	2.4 - 2.6 V
		When vehicle is being driven	0.5 - 4.5 V

The MUT-II/III can be used to force-drive all solenoid valves and the pump motor.