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 C0278 00: Brake Pedal Position Sensor Not CalibratedDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Brake Pedal Position Sensor 5-Volt Reference | C0277 06, C0870 03 | C0277 06 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Relay B+ | 2 | 2 | -- | -- |
Brake Pedal Position Sensor Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09 |
Center High Mounted Stop Lamp (CHMSL) Relay Control | B3903 02 | B3903 05 | B3903 05 | -- |
Center High Mounted Stop Lamp (CHMSL) Control | 2 | 2 | 2 | -- |
Left Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Brake Pedal Position Sensor Low Reference | -- | C0277 07 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 2 | 1 | -- |
Left Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Relay Ground | -- | 2 | -- | -- |
1. Stop Lamps Malfunction 2. Center High Mounted Stop Lamp (CHMSL) Malfunction | ||||
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 voltage to the center high mounted stop lamp (CHMSL) relay coil. When the CHMSL relay receives voltage from the BCM, the relay coil is energized and the CHMSL relay switch contacts close applying battery voltage to the CHMSL, transmission control module (TCM), and engine control module (ECM).
Conditions for Running the DTC
Battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
C0278 00
This DTC 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. |
| • | A history DTC will clear once 50 malfunction-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Verify that the DTC sets under the Conditions for Running and Setting.
- Perform the brake pedal position sensor recalibration procedure. Refer to Brake Pedal Position Sensor Calibration.
- 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 after completing the diagnostic procedure.
