For 1990-2009 cars

### 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 Calibrated

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Brake Pedal Position Sensor 5-Volt Reference | C0870 03 | C0870 03 | C0870 07 | --
Brake Pedal Position Sensor Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09
Stop Lamp Switch Signal | B3903 02, P0572 | B3903 05, P0573 | B3903 05, P0573 | --
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 06 | C0277 07 | --
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 1 | -- | --
Left Rear Stop/Turn Lamp Ground | -- | 1 | -- | --
Right Rear Stop/Turn 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 positive voltage to the stop lamps, center high mounted stop lamp (CHMSL), transmission control module (TCM), 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.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Verify 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 after completing the diagnostic procedure.

• | Brake Pedal Position Sensor Calibration

• | Brake Pedal Position Sensor Replacement