B1863
Auxiliary Brake System - Trailer Brake Control (TBC) Module
Pinpoint Test A: DTC B1863
Normal Operation
When a trailer is connected to the vehicle through the 7-pin trailer connector, the Trailer Brake Control (TBC) module will utilize the trailer as a secondary ground. When the brake pedal is applied, the TBC (Trailer Brake Control) module will send a Pulse Width Modulated (PWM) voltage to the brake solenoids on the trailer to activate the trailer brakes. Releasing the brake pedal creates a feed-back voltage spike that is monitored by the TBC (Trailer Brake Control) module. Normally, this voltage travels through a diode inside the module and is grounded into the vehicle along circuit GD116 (BK/VT). However, if a condition should occur that prevents the voltage from grounding along circuit GD116 (BK/VT), this feed-back voltage will create a voltage potential in the TBC (Trailer Brake Control) module, this voltage potential is detected by the module and, if the potential is greater than 19 volts, DTC B1863 will be set.
When DTC B1863 is set, the TBC (Trailer Brake Control) module will disable trailer braking in order to protect the module from additional voltage spikes and the module will also send a TBC (Trailer Brake Control) FAULT message to the message center.
- DTC B1863 (TBC (Trailer Brake Control) Ground Open Circuit)- An open circuit condition in GD116 (BK/VT) or an internal failure of the TBC (Trailer Brake Control) module will cause DTC B1863 to set. Unlike the other TBC (Trailer Brake Control) module DTCs, a trailermust be connected to the 7-pin trailer connector for DTC B1863 to set during an on-demand self test.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- TBC (Trailer Brake Control) module
PINPOINT TEST A : 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.
A1 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 C2142-11, circuit GD116 (BK/VT), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to A2.
No
REPAIR circuit GD116 (BK/VT). CLEAR the DTCs. REPEAT the self-test.
A2 CHECK FOR CORRECT TBC (Trailer Brake Control) MODULE OPERATION
- Check the TBC (Trailer Brake Control) module connector for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: TBC (Trailer Brake Control) Module C2142.
- Make sure the connector is seated correctly, then 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 Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.