U0252

U0252-LOST COMMUNICATION WITH TRAILER LIGHTING MODULE





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the ignition on.

Battery voltage between 10 and 16 volts.

IOD fuse installed.

FCM is configured correctly.

- Set Condition:
Bus messages not received from the Trailer Lighting Module (TM) for approximately 2 to 5 seconds.





Diagnostic Test

1. VERIFY DTC IS ACTIVE
NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.

With the scan tool, read active DTC's.
Is this DTC active?

Yes

- Go To 2

No

- Refer to the Stored Lost Communication test procedure Communications - Verbose Codes .

2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTC'S
With the scan tool, read active DTC's from all modules.

NOTE: Check for FCM configuration, CAN B or C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTC's.

Does the scan tool display any active DTC's to the conditions listed above?

Yes

- Diagnose and repair the DTC.

No

- Go To 3

3. VERIFY THAT THE TM IS ACTIVE ON THE BUS
Turn the ignition on.
With the scan tool, select Network View and select Advanced.

NOTE: A red X will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.

Verify that the TM is active on the bus.
Is the TM active on the bus?

Yes

- Replace and program the Front Control Module.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

No

- Go To 4

4. (A922) (A907) FUSED B(+) CIRCUITS OPEN




Turn the ignition off.
Disconnect the Trailer Lighting Module C2 harness connector.
Using a 12-volt test light connected to ground, check the (A922) and (A907) Fused B(+) circuits.
Does the test light illuminate brightly on each circuit?

Yes

- Go To 5

No

- Repair the (A922) or (A907) Fused B(+) circuit for an open or short.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

5. (F941) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT OPEN




Turn the ignition on.
Disconnect the Trailer Lighting Module C4 harness connector.
Using a 12-volt test light connected to ground, check the (F941) Fused Ignition Switch Output circuit.
Does the test light illuminate brightly?

Yes

- Go To 6

No

- Repair the (F941) Fused Ignition Switch Output circuit for an open or short.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

6. (Z923) GROUND CIRCUIT OPEN




Using a 12-volt test light connected to 12-volts, check the (Z923) ground circuit.
Does the test light illuminate brightly?

Yes

- Go To 7

No

- Repair the (Z923) ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

7. (D55) AND (D54) CAN B BUS CIRCUITS OPEN




NOTE: One open circuit will not cause this condition.

Measure the voltage between the (D54) CAN B Bus (-) circuit and ground.
Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.
Is there any voltage present on either circuit?

Yes

- Replace the Trailer Lighting Module.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.

No

- Repair the (D55) and (D54) CAN B Bus circuits for an open. Inspect the connector for damage.
- Perform BODY VERIFICATION TEST - VER 1.Body Verification Test.