Pinpoint Test I: DTC U0140

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Pinpoint Test I: DTC U0140

Normal Operation

- DTC U0140 (Lost Communication With Body Control Module (GEM))- sets in the Trailer Brake Control (TBC) module if data messages such as ignition state, park lamp status and illumination dimming level data are not received from the Body Control Module (BCM). For a complete list of all network messages, refer to Information Bus.

This pinpoint test is intended to diagnose the following:

- BCM (Body Control Module)

- TBC (Trailer Brake Control) module

PINPOINT TEST I : DTC U0140

I1 VERIFY THE CUSTOMER CONCERN

- Ignition ON.

- Verify that there is an observable symptom present.

Is an observable symptom present?

Yes
GO to I2.

No
The system is operating normally at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

I2 CHECK THE COMMUNICATION NETWORK

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Network Test.

- Carry out the network test.

Does the BCM (Body Control Module) module pass the network test?

Yes
GO to I3.

No
REFER to Information Bus.

I3 RETRIEVE THE RECORDED DTCs FROM THE TBC (Trailer Brake Control) MODULE SELF-TEST

- Check for recorded TBC (Trailer Brake Control) module DTCs from the self-test.

Is DTC B1317 or DTC B1318 recorded?

Yes
For DTC B1317, GO to Pinpoint Test D. Pinpoint Test D: DTC B1317

For DTC B1318, GO to Pinpoint Test E. Pinpoint Test E: DTC B1318
No
GO to I4.

I4 RECHECK THE TBC (Trailer Brake Control) MODULE DTCs

NOTE: If new modules were installed prior to the DTC being set, the module configuration may be incorrectly set during Programmable Module Installation (PMI) or the PMI (Programmable Module Installation) may not have been carried out.

- Clear the DTCs. Repeat the TBC (Trailer Brake Control) module self-test.

Is DTC U0140 still present?

Yes
GO to I5.

No
The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

I5 CHECK FOR DTC U0140 SET IN OTHER MODULES

- Clear the DTCs.

- Ignition OFF.

- Ignition ON.

- Wait 10 seconds.

- Using the scan tool, retrieve the continuous memory DTCs from all modules.

Is DTC U0140 set in the PCM?

Yes
INSTALL a new BCM (Body Control Module). REPEAT the BCM (Body Control Module) self-test.

No
INSTALL a new TBC (Trailer Brake Control) module. REFER to Trailer Brake Control (TBC) Module . TEST the system for normal operation.