For 1990-2009 cars only
Diagnostic Instructions
| • | 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. |
DTC Descriptor
DTC C0845 03: Device Ignition 1 Circuit Voltage Below ThresholdDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 | C0845 03 | C0845 03 | -- | -- |
TCC Brake Signal | C0845 03 | -- | -- | -- |
Circuit/System Description
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.
Conditions for Running the DTC
Engine running.
Conditions for Setting the DTC
The TBCM detects that the IGN 1 voltage is less than 9.2 volts
Action Taken When the DTC Sets
| • | 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. |
Conditions for Clearing the DTC
| • | 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. |
Reference Information
Schematic Reference
Trailer Brake Control Schematics
Connector End View Reference
Description and Operation
Trailer Brake Controls Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Verify that DTC B3445, C0277, C0297, or C0890 are not set.
- Ignition OFF, disconnect the harness connector of the TBCM.
- Ignition ON, test for greater than 11 volts between the IGN 1 voltage circuit terminal 15 and ground.
- If all circuits test normal, replace the TBCM.
| ⇒ | 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) |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
