Diagnosis Procedure

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.

With CONSULT 

1. Connect 4WAS main control unit harness connector.
2. Connect IPDM E/R harness connector.
3. Perform self-diagnosis for "4WAS(MAIN)/RAS/HICAS".

   Is DTC "C1909" detected? 

   YES: 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 ".

   NO: GO TO 5.

With CONSULT 

Check the "DATA MONITOR" value of each DTC detected with the self-diagnosis function. Refer to "REFERENCE VALUE ".

Is each data the standard value? 

YES: Check each harness connector pin terminal for disconnection.

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 ".