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 Descriptor

DTC P0573 : Brake Switch Circuit 1 High Voltage

Diagnostic 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 Switch Signal

B3903 02, P0572

B3903 05, P0573

B3903 05, P0573

--

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

--

Left Rear Stop/Turn Lamp Ground

--

1

1

--

Right 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, 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

    • The ignition is ON.
    • Battery voltage is greater than 11.5 volts.

Conditions for Setting the DTC

This DTC will set when the ECM detects an open or short to voltage on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are applied.

Action Taken When the DTC Sets

    • The ECM stores the DTC to memory.
    • The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.

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 40 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 .

Verify that the brake pedal position sensor is properly calibrated.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

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

Scan Tool Reference

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

Circuit/System Testing

  1. Ignition OFF, disconnect the appropriate harness connector at the ECM.
  2. Connect a test lamp between stop lamp switch signal circuit and ground.
  3. Ignition ON, apply the brake pedal ON and OFF. The test lamp should turn ON and OFF as the brake pedal is applied and released.
  4. If the test lamp is always ON, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Brake Pedal Position Sensor Calibration
    •  Control Module References for BCM and ECM replacement, setup, and programming

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 P0573 : Brake Switch Circuit 1 High Voltage

Diagnostic 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 Switch Signal

B3903 02, P0572

B3903 05, P0573

B3903 05, P0573

--

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

--

Left Rear Stop/Turn Lamp Ground

--

1

1

--

Right 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, 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

    • The ignition is ON.
    • Battery voltage is greater than 11.5 volts.

Conditions for Setting the DTC

This DTC will set when the ECM detects an open or short to voltage on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are applied.

Action Taken When the DTC Sets

    • The ECM stores the DTC to memory.
    • The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.

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 40 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 .

Verify that the brake pedal position sensor is properly calibrated.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

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

Scan Tool Reference

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

Circuit/System Testing

  1. Ignition OFF, disconnect the appropriate harness connector at the ECM.
  2. Connect a test lamp between stop lamp switch signal circuit and ground.
  3. Ignition ON, apply the brake pedal ON and OFF. The test lamp should turn ON and OFF as the brake pedal is applied and released.
  4. If the test lamp is always ON, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Brake Pedal Position Sensor Calibration
    •  Control Module References for BCM or ECM replacement, setup, and programming