C0278

DTC C0278

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (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 C0278 00
- Brake Pedal Position Sensor Not Calibrated




Diagnostic Fault Information






Circuit/System Description

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).


Conditions for Running the DTC

Battery voltage must be between 9-16 volts.


Conditions for Setting the DTC

DTC C0278 00 will set when the brake pedal position sensor home position is not learned.


Actions Taken When the DTC Sets

* The Service Vehicle Soon indicator is commanded ON.
* When DTC C0278 is set as current, the vehicle will not start.
* Stop lamps may not activate at the expected brake pedal positions.



Conditions for Clearing the DTC

* A successful brake pedal position sensor calibration has been performed.
* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 50 malfunction-free ignition cycles have occurred.



Diagnostic Aids

Important: The stop lamps will not illuminate unless the ignition is in the ON position. For more detailed information concerning stop lamp operation, refer to Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation) .



If DTC C0278 00 is set, recalibrate the brake pedal position sensor.


Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems 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)


Circuit/System Testing

1. Verify that the DTC sets under the Conditions for Running and Setting.
2. Perform the brake pedal position sensor recalibration procedure.
3. Operate the vehicle within the conditions that the customer experienced and verify the DTC does not reset.

• If the DTC resets, replace the brake pedal position sensor.




Repair Instructions

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

* Brake Pedal Position Sensor Calibration (Programming and Relearning)
* Brake Pedal Position Sensor Replacement (Brake Pedal Position Sensor Replacement)