C0845

DTC C0845

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC C0845 03
- Device Ignition 1 Circuit Voltage Below Threshold

Diagnostic Fault Information





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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Trailer Brake Controls Description and Operation (Trailer Brake Controls Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Verify that DTC B3445, C0277, C0297, or C0890 are not set.

• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions).

2. Ignition OFF, disconnect the harness connector of the TBCM.
3. Ignition ON, test for greater than 11 volts between the IGN 1 voltage circuit terminal 15 and ground.

• 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)

4. If all circuits test normal, replace the TBCM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for TBCM replacement, setup, and programming