DTC P1A02[7F] Lower Relay Circuit (OFF Error) (Differential Lock)

1. Differential lock control system check

Refer to "53.Driveline Control 3A.Troubleshooting(Differential Lock) diagnostic system check - differential lock controls".

2. Current DTC check

1) Connect the scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Turn ON the ignition switch.

4) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to Differential lock coil low-side control circuit inspection.

No

Go to Intermittent conditions of rear differential lock control system.

Refer to "204.Driveline, Axle 17D.Symptom intermittent conditions of differential lock control system".

3. Differential lock coil low-side control circuit inspection

1) Turn OFF the ignition switch.

2) Disconnect the rear differential lock control unit harness connector (C57) and differential lock coil harness connector (R39).

3) Inspect the wire harnesses and connectors for the following. Is the result normal?

Wire harness to be inspected

  • Between the rear differential lock control unit (pin 7 of C57) and the differential lock coil (pin 2 of R39)

Refer to "LHD Differential Lock" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Differential Lock" in the ETM (wiring diagram). (Open using the ETM viewer.).

Inspection items

  • Short to power supply or short to other circuits
  • Short to ground or short to other circuits
  • Corrosion or water intrusion in the terminal

Yes

=>Go to Rear differential lock control unit replacement.

No

Repair the circuit as necessary.

=>Go to Repair verification.

4. Rear differential lock control unit replacement

Note

  • Perform programming after replacing the rear differential lock control unit.

Refer to "3.Driveline, Axle 3Z.Driveline, Axle Electrical Control rear differential lock control unit removal".

Refer to "3.Driveline, Axle 3Z.Driveline, Axle Electrical Control rear differential lock control unit installation".

Refer to "3.Driveline, Axle 3Z.Driveline, Axle Electrical Control rear differential lock control unit setting".

Procedure completion

=>Go to Repair verification.

5. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Turn ON the ignition switch.

4) Observe the DTC information with a scan tool.