Trailer Brake Control Module: Description and Operation

Auxiliary Brake System - Trailer Brake Control (TBC) Module

Trailer Brake Control System

The trailer brake control system consists of the following components:

- Trailer Brake Control (TBC) module, which is mounted in the center of the instrument panel just below the climate controls

- Trailer tow connector

- Instrument Panel Cluster (IPC)

The TBC (Trailer Brake Control) module has the following driver inputs and outputs:

- Manual slider switch (input)

- Gain buttons (input)

- Gain setting display (output)

- Trailer connectivity icon (output)

- Output bar graph display (output)

The manual slider switch on the TBC (Trailer Brake Control) module is used to activate the trailer brakes independently from the vehicle brakes. The manual slider is used in conjunction with the gain buttons to adjust and set the trailer brakes. When the manual lever is activated with a trailer connected to the vehicle, the trailer stoplamps and the vehicle stoplamps illuminate. Activating the manual lever without a trailer connected to the vehicle still illuminates the vehicle stoplamps.

The gain buttons are used to set the TBC (Trailer Brake Control) system for specific towing conditions such as trailer load, vehicle load, road conditions and weather. The gain is normally set to provide maximum trailer braking while maintaining trailer stability. For information on setting the trailer brake gain, refer to the Owner's Literature.

The displays are used to provide the driver with TBC (Trailer Brake Control) system information. Trailer connectivity is provided through the trailer connector icon, the gain setting display provides the driver with the current gain setting and the output bar graph shows the amount of power going to the trailer brakes relative to brake pedal or manual lever input (only if a trailer is connected to the vehicle).

TBC (Trailer Brake Control) System Message Center Messages

The IPC (Instrument Panel Cluster) message center displays the gain setting and relative braking power during a braking event. The message center also indicates trailer connectivity and trailer wiring faults. The following message center messages pertain to the TBC (Trailer Brake Control) system:

- NO TRAILER- This message is displayed whenever the ignition is cycled from OFF to RUN without a trailer connected to the 7-pin trailer connector.

- TRAILER CONNECTED- This message is displayed when a correct trailer connection at the 7-pin trailer connector has been made during a given ignition cycle.

- OUTPUT- When the vehicle brake pedal is applied, or when the manual control is activated, bar indicators illuminate in the message center to indicate the amount of power going to the trailer brakes relative to the brake pedal or manual control input. One bar indicates the least amount of output with 6 bars indicating maximum output.

- TRAILER DISCONNECTED- This message is displayed and accompanied by a single chime when a correct trailer connection was made and then a disconnection has been sensed during a given ignition cycle. This message displayed if the 7-pin trailer connector becomes disconnected while driving. This message can be displayed if an intermittent open circuit occurs in the vehicle wiring from the TBC (Trailer Brake Control) module to the 7-pin trailer connector or the trailer wiring. This message is also displayed accompanied by a single chime during manual activation using the manual control lever without a trailer connected.

- TRAILER BRAKE MODULE FAULT- This message is displayed when a fault is detected by the TBC (Trailer Brake Control) module. A DTC is stored in the TBC (Trailer Brake Control) module when this message is displayed.

- WIRING FAULT ON TRAILER- This message is displayed when the trailer brake output circuit is shorted to ground or shorted to voltage. A DTC is set in the TBC (Trailer Brake Control) module indicating which circuit fault was observed. It is important to determine if a trailer was connected when this message was displayed. If this message is only observed with a trailer is connected, the concern is related to the trailer wiring and not the vehicle. If this message is observed without a trailer connected, the the concern is with the vehicle wiring from the TBC (Trailer Brake Control) module to the 7-pin trailer connector.

- TBC FAULT- The message center displays this if the Instrument Panel Cluster (IPC) is receiving communications from the TBC (Trailer Brake Control) module, but has not been configured for a trailer brake system. If the message center displays TBC (Trailer Brake Control) FAULT and there are no DTCs stored in the TBC (Trailer Brake Control) module, follow the steps in Programmable Parameters to verify and/or modify the TBC (Trailer Brake Control) module programmable parameter in the IPC (Instrument Panel Cluster).