TBC System Message Center Messages
Auxiliary Brake System - Trailer Brake Control (TBC) Module
TBC System Message Center Messages
The IC message center provides the gain setting and relative braking power during a braking event. The message center will also indicate trailer connectivity and trailer wiring faults. The following message center messages pertain to the TBC system:
- NO TRAILER - This message is displayed and accompanied by a single chime 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 pushed, or when the manual control is activated, bar indicators will 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 will display 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 module to the 7-pin trailer connector or the trailer wiring. This message is also displayed 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 module. A DTC will be stored in the TBC 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 will be set in the TBC 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, problem is related to the trailer wiring and not the vehicle. If this message is observed without a trailer connected, the problem is with the vehicle wiring from the TBC module to the 7-pin trailer connector.
Trailer Brake Control (TBC) Module Wake Up
NOTE: These conditions require that a trailer is not connected to the trailer tow connector.
The following conditions describe the normal operation of the TBC module at start up.
When the ignition key is in the RUN position and the manual lever is set all the way to the left with a gain of 10, without a trailer connected to the vehicle, the message center should display TRAILER DISCONNECTED. At the same time, with the vehicle stationary, battery voltage should be present at pin-3 of trailer tow connector C4099.
Every 4 seconds the TBC module sends a voltage pulse along circuit CAT19 (BU) to pin-3 of trailer tow C4099 to determine whether a trailer is connected to the trailer tow connector.