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 C0277 06: Brake Pedal Position Sensor Circuit Short to Ground or open
DTC C0277 07: Brake Pedal Position Sensor Circuit Short to Battery
DTC C0277 09: Brake Pedal Position Sensor Circuit To Fast Transitions
DTC C0277 4B: Brake Pedal Position Sensor Circuit Calibration Not Learned

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
5-Volt Reference | C0277 06 | C0277 06 | C0277 07 | --
Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09
Low Reference | -- | 1 | -- | --
1 Stop Lamps Malfunction

### Circuit/System Description

The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position (BPP) 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 (BPP) 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 control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 V.

• | Brakes applied.

### Conditions for Setting the DTC

#### C0277 06

• | The BCM detects a short to ground or an open/high resistance in the brake pedal position (BPP) sensor signal circuit.

• | The BCM detects a short to ground or an open/high resistance in the brake pedal position (BPP) sensor 5-volt reference circuit.

#### C0277 07

• | The BCM detects a short to battery voltage in the brake pedal position (BPP) sensor signal circuit.

• | The BCM detects an open/high resistance in the brake pedal position (BPP) sensor low reference circuit.

#### C0277 09

The DTC will set when the BCM detects the brake pedal position (BPP) sensor signal is changing faster than possible under normal operating conditions.

#### C0277 4B

The DTC will set when the brake pedal position (BPP) sensor home position is not learned.

### Conditions for Clearing the DTC

The condition for setting the DTC is not longer present.

### Diagnostic Aids

#### C0277 4B

If the DTC is set, recalibrate the brake pedal position (BPP) sensor.

#### C0277 09

If the DTC is set, replace the brake pedal position (BPP) sensor. If the DTC resets, replace the BCM.

### 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 Verification

Ignition ON, observe the scan tool Brake Switch parameter. The reading should be between Inactive/Active and change when the brake pedal is pushed or released.

### Circuit/System Testing

#### C0277 06 or C0277 07

1. Ignition OFF, disconnect the harness connector at the B22 Brake Pedal Position (BPP) Sensor.
2. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal C and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

3. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal A and ground.

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

4. Test for 4.8-5.2 V between the 5-volt signal circuit terminal B and ground.

⇒ | If less than the specified range, test the 5-volt signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If greater than the specified range, test the 5-volt signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

5. If all circuits test normal, test or replace the B22 Brake Pedal Position (BPP) Sensor.

#### C0277 09

1. If the DTC is set, replace the brake pedal position (BPP) sensor.
2. Perform the brake pedal position sensor recalibration procedure. Refer to Brake Pedal Position Sensor Calibration
3. Operate the vehicle within the Conditions for Running and Setting the DTC and verify the DTC does not reset.

⇒ | If the DTC resets, replace the K9 Body Control Module (BCM).

#### C0277 4B

If the DTC is set, recalibrate the brake pedal position (BPP) sensor.

1. Verify that the DTC sets under the conditions for running and setting.
2. Perform the brake pedal position sensor recalibration procedure. Refer to Brake Pedal Position Sensor Calibration
3. Operate the vehicle within the Conditions for Running and Setting the DTC and verify the DTC does not reset.

⇒ | If the DTC resets, replace the B22 Brake Pedal Position (BPP) Sensor.

### Component Testing

#### Static Test

1. Ignition OFF, disconnect the harness connector at the B22 Brake Pedal Position (BPP) Sensor.
2. Test for 10 Ω between the 5-volt reference terminal A and the low reference terminal C.

⇒ | If not within the specified range, replace the B22 Brake Pedal Position (BPP) Sensor.

3. Sweep the sensor through the entire range while monitoring the resistance between the signal terminal B and the low reference terminal C. The resistance should vary between 10-20 Ω without any spikes or dropouts.

⇒ | If not within the specified range or is erratic, replace the B22 Brake Pedal Position (BPP) Sensor.

4. Test for infinite resistance between each terminal and the sensor housing/case.

⇒ | If not the specified value, replace the B22 Brake Pedal Position (BPP) Sensor.

#### Dynamic Test

1. Install a 3 A fused jumper wire between the 5-volt reference terminal A and 5 V. Install a jumper wire between the low reference terminal C and ground.
2. Sweep the sensor through the entire range while monitoring the voltage between the signal terminal B and the low reference terminal C. The voltage should vary between 0.5-4.5 V without any spikes or dropouts.

⇒ | If not within the specified range or is erratic, replace the B22 Brake Pedal Position (BPP) Sensor.

### Repair Instructions

• | Brake Pedal Position Sensor Calibration

• | Stop Lamp Switch Replacement

• | Control Module References for BCM replacement, setup and programming

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.