Pinpoint Test F: DTC B1863

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Pinpoint Test F: DTC B1863

Normal Operation

The Trailer Brake Control (TBC) module receives battery voltage from Battery Junction Box (BJB) fuse 17 (30A) and ignition voltage from Body Control Module (BCM) fuse 37 (10A).

- DTC B1863 (TBC (Trailer Brake Control) Ground Open Circuit)- this DTC sets in continuous memory or on-demand when the TBC (Trailer Brake Control) module detects an open circuit in the wiring, a connector condition causes an open in the ground circuit or if an internal failure of the TBC (Trailer Brake Control) module causes an open in the ground circuit. The TBC (Trailer Brake Control) module also disables trailer braking and sends a TRAILER BRAKE MODULE FAULT message to the message center. A trailer must be connected for this DTC to set.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- TBC (Trailer Brake Control) module

PINPOINT TEST F : DTC B1863

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
NOTE:
A trailer must be connected to the 7-pin trailer connector for DTC B1863 to set during the on-demand self-test.

F1 CHECK THE TBC (Trailer Brake Control) MODULE GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: TBC (Trailer Brake Control) Module C2142.

- Measure the resistance between TBC (Trailer Brake Control) module C2142-3, circuit GD138 (BK/WH), harness side and ground.






Is the resistance less than 5 ohms?

Yes
GO to F2.
No
REPAIR circuit GD138 (BK/WH). CLEAR the DTCs. REPEAT the self-test.

F2 CHECK FOR CORRECT TBC (Trailer Brake Control) MODULE OPERATION

- Disconnect the TBC (Trailer Brake Control) module connector.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect the TBC (Trailer Brake Control) module connector and make sure it seats correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new TBC (Trailer Brake Control) module. REFER to Trailer Brake Control (TBC) Module . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.