P1811

P1801, P1811 POWER SUPPLY CIRCUIT FOR TRANSFER CONTROL UNIT





Description
The transfer control unit controls the transfer control device which controls shifts between 4H and 4LO and between 2WD and 4WD. When the vehicle battery is removed, the power supply to the transfer control unit is interrupted, and self-diagnosis memory function is suspended. These DTCs may also set when the power supply voltage for the transfer control unit is abnormally low while driving.




DTC Logic

DTC DETECTION LOGIC






DTC CONFIRMATION PROCEDURE
1.DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Perform self-diagnosis.
Are DTCs "P1801 or P1811 detected?
YES - Perform diagnosis procedure. SEE Diagnosis Procedure.
NO - Inspection End.




Diagnosis Procedure
Regarding Wiring Diagram information, [1][2]Electrical Diagrams.
1.CHECK POWER SUPPLY
1. Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2. Disconnect transfer control unit harness connector.





3. Check voltage between transfer control unit harness connector terminals and ground.










4. Turn ignition switch "ON". (Do not start engine.)
5. Check voltage between transfer control unit harness connector terminals and ground.






Is there voltage?
YES - GO TO 2.
NO - Check the following. If any items are damaged, repair or replace damaged parts.
- 40A fuse (No. J, located in the fuse and fusible link box).
- 10A fuses (No. 21, located in the fuse block (J/B) and Nos. 57 and 58 located in the fuse and relay box).
- Harness for short or open between battery and transfer control unit harness connector M152 terminal 19.
- Harness for short or open between battery and transfer shut off relay 2 harness connector E157 terminal 1 and 3.
- Harness for short or open between battery and transfer shut off relay 1 harness connector E156 terminal 3.
- Harness for short or open between ignition switch and transfer control unit harness connector
M152 terminal 25.
- Harness for short or open between ignition switch and transfer shut off relay 1 harness connector E156 terminal 1.
- Harness for short or open between transfer shut off relay 2 harness connector E157 terminal 5 and transfer control unit harness connector M153 terminals 44, 45.
- Harness for short or open between transfer shut off relay 1 harness connector E156 terminal 5 and transfer control unit harness connector M153 terminals 44, 45.
- Harness for short or open between transfer shut off relay 2 harness connector E157 terminal 2 and transfer control unit harness connector M153 terminal 40.
- Harness for open between transfer shut off relay 1 harness connector E156 terminal 2 and ground.
- Battery and ignition switch.
- Transfer shut off relay 1, 2. SEE Component Inspection.
2.CHECK GROUND CIRCUIT
1. Turn ignition switch "OFF".
2. Disconnect transfer control unit harness connector.





3. Check continuity between transfer control unit harness connector M152 terminals 6 (M/T models) and 18, and M153 terminal 32 and ground.






Also check harness for short to power.
Do you have continuity?
YES - GO TO 3.
NO - Repair open circuit or short to power in harness or connectors.
3.CHECK TRANSFER CONTROL UNIT
Check transfer control unit input/output signal. Pinout Values and Diagnostic Parameters.
Are the inspection results normal?
YES - GO TO 4.
NO - Check transfer control unit pin terminals for damage or loose connection with harness connector.
If any items are damaged, repair or replace damaged parts.
4.CHECK DTC
Drive vehicle and then perform Self-diagnosis.
Do DTCs P1801 or P1811 display?
YES - Replace transfer control unit. Service and Repair.
NO - Inspection End.




Component Inspection
1. Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2. Remove transfer shut off relay 1 and transfer shut off relay 2. SEE Component Inspection.





3. Apply 12V direct current between transfer shut off relay terminals 1 and 2.
4. Check continuity between relay terminals 3 and 5.





5. If inspection results are not normal, replace the transfer shut off relay 1 or 2.