• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Ignition 1 | C0845 03 | C0845 03 | -- | -- |
TCC Brake Signal | C0845 03 | -- | -- | -- |
The trailer brake control module (TBCM) monitors the ignition circuit. This diagnostic compares ignition state with the engine running state received over serial data to determine if there is an ignition circuit fault.
Engine running.
The TBCM detects that the IGN 1 voltage is less than 9.2 volts
• | The trailer brake control will be disabled for the remainder of the ignition cycle. |
• | The driver information center (DIC) will display Service Trailer Brake System. |
• | The condition for the DTC is no longer present. |
• | The TBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles. |
Trailer Brake Control Schematics
Trailer Brake Controls Description and Operation
• | Circuit Testing |
• | Wiring Repairs |
Control Module References for scan tool information
⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
⇒ | If less than the specified voltage, test the IGN 1 voltage circuit for a short to ground or an open/high resistance. If the circuit test normal and the MISC - IGN fuse listed below is open, test the signal circuit terminal 37 for a short to ground. If the circuit tests normal, test or replace the RUN/CRANK relay. |
• | Fuse 43 (Gas) |
• | Fuse 40 (Diesel) |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming