Diagnosis Procedure (4WAS Main Control Unit)

1. Turn the ignition switch OFF.
2. Disconnect 4WAS main control unit harness connector.
3. Check the continuity between 4WAS main control unit harness connector terminal and the ground.

   4WAS main control unit		-	Continuity
   Connector	Terminal
   B54	34	Ground	Existed
   	40

   Is the inspection result normal? 

   YES: GO TO 2.

   NO: Repair or replace the harnesses and connectors.

1. Check the voltage between 4WAS main control unit harness connector terminal and ground.

   4WAS main control unit		-	Voltage (Approx.)
   Connector	Terminal
   B54	27	Ground	0 V

2. Turn the ignition switch ON.
   CAUTION: Never start the engine.
3. Check the voltage between 4WAS main control unit harness connector terminal and ground.

   4WAS main control unit		-	Voltage (Approx.)
   Connector	Terminal
   B54	27	Ground	Battery voltage

   Is the inspection result normal? 

   YES: GO TO  4.

   NO: GO TO 3.

1. Turn the ignition switch OFF.
2. Check the 10A fuse (#46).
3. Disconnect IPDM E/R harness connector.
4. Check the continuity between 4WAS main control unit harness connector and IPDM E/R harness connector.

   4WAS main control unit		IPDM E/R		Continuity
   Connector	Terminal	Connector	Terminal
   B54	27	E5	12	Existed

5. Check the continuity between 4WAS main control unit harness connector and ground.

   4WAS main control unit		-	Continuity
   Connector	Terminal
   B54	27	Ground	Not existed

   Is the inspection result normal? 

   YES: Perform the trouble diagnosis for ignition power supply circuit. Refer to "WIRING DIAGRAM - IGNITION POWER SUPPLY - ".

   NO: Repair or replace error-detected parts.

1. Remove 4WAS rear motor relay.
2. Check the continuity between 4WAS rear motor relay harness connector and ground.

   4WAS rear motor relay		-	Continuity
   Connector	Terminal
   B5	2	Ground	Existed
   	1		Not existed

3. Check the continuity between 4WAS main control unit harness connector and IPDM E/R harness connector.

   4WAS rear motor relay		4WAS main control unit		Continuity
   Connector	Terminal	Connector	Terminal
   B53	1	B54	25	Existed

   Is the inspection result normal? 

   YES: GO TO 5.

   NO: Repair or replace error-detected parts.

1. Check 20A fusible link (#37).
2. Check the harness for open or short between 4WAS front control unit harness connector No. 3 terminal and 20A fusible link (#37).

   Is the inspection result normal? 

   YES: GO TO 6.

   NO: Repair or replace error-detected parts.

1. Turn the ignition switch ON.
   CAUTION: Never start the engine.
2. Check the voltage between 4WAS main control unit harness connectors and the ground.

   4WAS main control unit		-	Voltage (Approx.)
   Connector	Terminal
   B54	25	Ground	Battery voltage

3. Turn the ignition switch OFF.

   Is the inspection result normal? 

   YES: GO TO 7.

   NO: Replace 4WAS main control unit. Refer to "REMOVAL AND INSTALLATION ".

   • Before replacing 4WAS main control unit, record the self-diagnosis results (history). Refer to "SPECIAL REPAIR REQUIREMENT ".

Check 4WAS rear motor relay. Refer to "COMPONENT INSPECTION ".

Is the inspection result normal? 

YES: GO TO 8.

NO: Replace 4WAS rear motor relay.

1. Connect 4WAS main control unit harness connector.
2. Install 4WAS rear motor relay.
3. Turn the ignition switch ON.
   CAUTION: Never start the engine.
4. Check the voltage between 4WAS main control unit harness connectors and the ground.

   4WAS main control unit		-	Voltage (Approx.)
   Connector	Terminal
   B54	37	Ground	Battery voltage

   Is the inspection result normal? 

   YES: INSPECTION END.

   NO: Replace 4WAS main control unit. Refer to "REMOVAL AND INSTALLATION ".

   • Before replacing 4WAS main control unit, record the self-diagnosis results (history). Refer to "SPECIAL REPAIR REQUIREMENT ".