C0800

DTC C0800

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) provide an overview of each diagnostic category.

DTC Descriptor
DTC C0800 03
- Device Power Circuit Voltage Below Threshold

DTC C0800 07
- Device Power Circuit Voltage Above Threshold

Circuit/System Description

The trailer brake control module (TBCM) monitors the battery voltage. Damage to components, and incorrect data input can occur when the voltage is out of range.

Conditions for Running the DTC

Engine running.

Conditions for Setting the DTC

C0800 03

During the system operation, the system voltage is less than 9.5 volts.

C0800 07

The system voltage is greater than 17 volts.

Action Taken When the DTC Sets

* The trailer brake control will be disabled at the end of the current brake apply 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 Verification

Engine running, observe the scan tool TBCM Battery Voltage Signal parameter. The reading should be between 12.6 and 15.0 volts.

Circuit/System Testing

1. Engine running, accessories OFF, measure the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 volts.

• If not within the specified range, refer to Charging System Test (Charging System Test).

2. Ignition OFF, disconnect the harness connector at the TBCM.
3. Ignition OFF, test for less than 5 ohms between the ground circuit terminal 1 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Verify that a test lamp illuminates between the B+ circuit terminal 32 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

5. 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