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 Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09 |
Brake Pedal Position Sensor 5-Volt Reference | C0870 03 | C0870 03 | C0870 07 | -- |
Brake Pedal Position Sensor Low Reference | -- | C0277 06 | C0277 07 | -- |
Stop Lamp Relay Control | B3903 02 | B3903 05 | B3903 05 | -- |
Left Rear Tail/Stop Lamp Supply Voltage | 1 | 1 | 1 | -- |
Right Rear Tail/Stop Lamp Supply Voltage | 1 | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 1 | -- | -- |
Left Rear Tail/Stop Lamp Ground | -- | 1 | -- | -- |
Right Rear Tail/Stop Lamp Ground | -- | 1 | -- | -- |
1. Stop Lamps 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 battery voltage to the stop lamp relay control circuit. This energizes the stop lamp relay coil causing the relay switch contacts to close. With the relay switch contacts closed, battery voltage flows from the STOP LAMP fuse through the relay switch contacts to the rear stop lamps, center high mounted stop lamp (CHMSL), and engine control module (ECM). The stop lamps will not operate unless the ignition is in the ON position.
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 MIL/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. |
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.
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.
- 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.
