U0252-LOST COMMUNICATION WITH TRAILER LIGHTING MODULE

For a complete wiring diagram Refer to Section 8W.

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.

Possible Causes

CAN B BUS CIRCUITS OPEN

DTC'S RELATED TO BATTERY VOLTAGE, IGNITION, OR VIN MESSAGES

FCM NOT CONFIGURED CORRECTLY

(A922) (A907) FUSED B(+) CIRCUIT OPEN OR SHORTED

(F941) FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN OR SHORTED

(Z923) GROUND CIRCUIT OPEN

TRAILER LIGHTING MODULE (TM)

FRONT CONTROL MODULE

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.

Is this DTC active?

Yes

Go To 2

Refer to the Stored Lost Communication test procedure. Refer to the table of contents in this section.

2.CHECK FOR ANY OF THE FOLLOWING ACTIVE DTC'S

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. Refer to the Index for a complete list of the symptoms.

Go To 3

3.VERIFY THAT THE TM IS ACTIVE ON THE BUS

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.

Is the TM active on the bus?

Yes

Replace and program the Front Control Module in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Go To 4

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

Does the test light illuminate brightly on each circuit?

Yes

Go To 5

Repair the (A922) or (A907) Fused B(+) circuit for an open or short.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

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

Does the test light illuminate brightly?

Yes

Go To 6

Repair the (F941) Fused Ignition Switch Output circuit for an open or short.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

6.(Z923) GROUND CIRCUIT OPEN

Does the test light illuminate brightly?

Yes

Go To 7

Repair the (Z923) ground circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

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

NOTE: One open circuit will not cause this condition.

Is there any voltage present on either circuit?

Yes

Replace the Trailer Lighting Module in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Repair the (D55) and (D54) CAN B Bus circuits for an open. Inspect the connector for damage.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).