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 P0719:  Brake Switch Circuit Low Voltage

DTC P0724:  Brake Switch Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Stop Lamp Switch Signal

P0719

P0719

P0724

--


Scan Tool Parameter Data

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running in PARK, normal operating temperature

Parameter Normal Range: Closed

TCC Brake Switch

Closed

Closed

Open

Circuit/System Description

The brake switch indicates brake pedal status to the transmission control module (TCM). The normally-closed brake switch supplies ignition voltage to the TCM. Applying the brake pedal opens the switch, interrupting voltage to the TCM. Releasing the brake pedal resumes voltage to the TCM.

Conditions for Running the DTC

P0719

    • No OSS DTCs P0722 or P0723.
    • DTC P0719 has not passed this ignition cycle.

P0724

    • No OSS DTCs P0722 or P0723.
    • DTC P0724 has not passed this ignition cycle.

Conditions for Setting the DTC

P0719

DTC P0719 sets if the TCM detects an open brake switch or circuit and the following conditions occur eight times:

    • The vehicle speed is greater than 32 km/h (20 mph) for 6 seconds;
    • then, the vehicle speed is 8-32 km/h (5-20 mph) for 6 seconds;
    • then, the vehicle speed is less than 8 km/h (5 mph) for 2 seconds.

P0724

DTC P0724 sets if the TCM detects a closed brake switch or circuit, 12 volts, for 15 minutes during vehicle acceleration and the following conditions occur eight times:

    • The vehicle speed is less than 8 km/h (5 mph) for 1 second;
    • then, the vehicle speed is 8-32 km/h (5-20 mph) for 6 seconds;
    • then, the vehicle speed is greater than 32 km/h (20 mph) for 6 seconds.

Action Taken When the DTC Sets

DTCs P0719 and P0724 are Type C DTCs.

Conditions for Clearing the DTC

DTCs P0719 and P0724 are Type C DTCs.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Start the engine. With the vehicle in Park and at normal operating temperature, observe the TCC Brake Switch parameter on the scan tool. The TCC Brake Switch parameter should display Closed with the brake pedal released. Apply the brake pedal and the TCC Brake Switch parameter should display Open.

Circuit/System Testing

  1. Install a scan tool. Turn ON the ignition, leaving the engine OFF. Observe the TCC Brake Switch parameter. The parameter should display Closed.
  2. If the scan tool displays Open, disconnect the stop lamp switch connector.
  3. Observe the TCC Brake Switch parameter on the scan tool with the stop lamp switch connector disconnected. The parameter should display Open.
  4. If the scan tool displays Closed after the stop lamp switch connector disconnected, test the stop lamp switch.
    If the scan tool displays Open after the stop lamp switch connector is disconnected, test the stop lamp switch signal circuit for a short to voltage.
  5. While observing the TCC brake switch parameter on the scan tool, use a terminal test kit and install a fused jumper wire between the ignition 1 voltage circuit and the stop lamp switch signal circuit. The TCC brake switch parameter should change from Closed to Open when the fused jumper wire is installed.
  6. If the TCC brake switch parameter changes, replace the stop lamp switch.
  7. Inspect the STOP LPS fuse. Refer to Circuit Protection - Fuses. The fuse should not be blown.
  8. If the fuse is blown, test the ignition 1 voltage circuit and the stop lamp switch signal circuit for a short to ground.
  9. Using a DMM, measure the voltage between the ignition 1 voltage circuit and ground at the stop lamp switch connector. The voltage should be near 12 volts.
  10. If the voltage is not near the specified voltage, test the ignition 1 voltage circuit for an open or high resistance.
  11. Using a terminal test kit measure the resistance of the stop lamp switch signal circuit between the BCM and the stop lamp switch. The resistance should be less than 10 ohms.
  12. If the resistance is greater than 10 ohms, test the stop lamp switch signal circuit for an open or high resistance.
    If all circuits and connections test normal, replace the BCM.

Component Testing

Inspect the stop lamp switch for proper adjustment; refer to Stop Lamp Switch Replacement. With the stop lamp switch removed, use a DMM to measure to resistance across the pins for the ignition 1 voltage circuit and the stop lamp switch signal circuit. With the plunger released on the stop lamp switch the resistance should display infinite on the DMM. With the plunger depressed on the stop lamp switch the resistance should display less than 10 ohms.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

    •  Output Speed Sensor Removal and Output Speed Sensor Installation
    •  Control Module References for BCM replacement, setup, and programming
    •  Stop Lamp Switch Replacement