C0278
DTC C0278
CIRCUIT 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).
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC C0278 Brake Pedal Position Sensor Not Calibrated
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information. DTC Symptom Description
CONDITIONS FOR RUNNING THE DTC
Ignition voltage is within the normal operating voltage range.
CONDITIONS FOR SETTING THE DTC
DTC C0278 00 will set when the brake pedal position sensor home position is not learned.
ACTION 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.
- If DTC C0278 00 is set, recalibrate the brake pedal position sensor.
- Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics
TEST
