GM Service Manual Online
For 1990-2009 cars only

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 Descriptors

DTC C0277 06: Brake Pedal Position Sensor Circuit Short to Ground or Open

DTC C0277 07: Brake Pedal Position Sensor Circuit Voltage Above Threshold

DTC C0277 09: Brake Pedal Position Sensor Circuit Rate of Change Above Threshold

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Brake Position Sensor Signal

C0277 06

C0277 06

C0277 07

C0277 09

Stop Lamp Relay Control

1

1

1

--

Stop Lamp Switch Signal

P0572, P0719

P0573, P0719

P0573, P0724

--

Stop Lamp Relay Switch B+

1

1

--

--

Brake Position Sensor 5-Volt Reference

C0870 03

C0870 03

C0870 07

--

Brake Position Sensor Low Reference

--

C0277 06

C0277 07

--

Left Rear Stop/Turn Lamp Supply Voltage

1

1

1

--

Right Rear Stop/Turn Lamp Supply Voltage

1

1

1

--

Center High Mounted Stop Lamp (CHMSL) Ground

--

1

1

--

Rear Stop/Turn Lamp Ground

--

1

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, 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).

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

C0277 06

This DTC will set when the BCM detects an open or short to ground in the brake pedal position sensor signal circuit for 0.5 seconds or greater.

C0277 07

This DTC will set when the BCM detects a short to battery voltage in the brake pedal position sensor signal or low reference circuits for 0.5 seconds or greater.

C0277 09

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

Actions Taken When the DTC Sets

    • The Service Vehicle Soon indicator is commanded ON.
    • When DTC C0277 is set as current, the vehicle will not start.
    • If the DTC sets while the vehicle is running, the BCM will activate the brake lights when the vehicles transmission is not in the PARK position and the vehicle is not accelerating.

Conditions for Clearing the DTC

    • 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.
    • A DTC will not clear the current status until the next ignition cycle.

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 C0277 09 is set, replace the brake pedal position sensor. If the DTC resets, replace the BCM.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the brake pedal position sensor.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal A and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
  5. 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 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 BCM.
  6. Verify the scan tool BPP sensor signal parameter is less than 0.2 volts.
  7. If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the BCM.
  8. Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool BPP sensor signal parameter is greater than 4.75 volts.
  9. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  10. If all circuits test normal, test or 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
    •  Control Module References for BCM replacement, setup, and programming