Pinpoint Test I: DTC U0140

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Pinpoint Tests

Pinpoint Test I: DTC U0140

Normal Operation
- DTC U0140 (Lost Communication With Body Control Module (GEM)) - this DTC sets in continuous memory or on-demand 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 Module Communications Network Testing and Inspection.

This pinpoint test is intended to diagnose the following:

- BCM
- TBC module

PINPOINT TEST I: DTC U0140

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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.

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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 module pass the network test?

Yes
GO to I3.

No
REFER to Module Communications Network Testing and Inspection.

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I3 RETRIEVE THE RECORDED DTCs FROM THE TBC MODULE SELF-TEST

- Check for recorded TBC module DTCs from the self-test.
- Is DTC B1317 or DTC B1318 recorded?

Yes
For DTC B1317, GO to Pinpoint Test D. For DTC B1318, GO to Pinpoint Test E. Pinpoint Test D: DTC B1317 Pinpoint Test E: DTC B1318

No
GO to I4.

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I4 RETRIEVE THE RECORDED DTCs FROM THE BCM SELF-TEST

- Check for recorded BCM DTCs from the self-test.
- Is DTC U3003:16 or DTC U3003:17 recorded?

Yes
REFER to Multifunction Electronic Modules Multifunction Electronic Modules.

No
GO to I5.

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I5 RECHECK THE TBC 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 may not have been carried out.

- Clear the DTCs. Repeat the TBC module self-test.
- Is DTC U0140 still present?

Yes
GO to I6.

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.

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I6 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. REFER to Multifunction Electronic Modules Service and Repair. REPEAT the BCM self-test.

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

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