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 ACTIVENOTE: 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. Refer to the table of contents in this section.
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. Refer to the Index for a complete list of the symptoms.
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 in accordance with the service information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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. (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.
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 in accordance with the service information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- 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).