P0724

DTC P0719 or P0724

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC P0719
- Brake Switch Circuit Low Voltage

DTC P0724
- Brake Switch Circuit High Voltage

Circuit/System Description

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

Conditions for Running the DTC

P0719
* No output speed sensor (OSS) DTCs P0722 or P0723.
* Brake Switch DTC P0724 has not passed.
* The TCM detects the brake switch is apply for 900 seconds.
* The vehicle speed is less than 8 km/h (5 mph) for greater than 6 seconds, then greater than 40 km/h (25 mph) for 6 seconds.
* Continuously 8 times once the previous criteria have been met.
* This DTC has not passed this ignition cycle.

P0724
* No OSS DTCs P0722 or P0723.
* No Brake Switch DTC P0719.
* The vehicle speed is less than 40 km/h (25 mph) for 6 seconds, then greater than 40 km/h (25 mph) for 7 seconds, then less than 8 km/h (5 mph).

Conditions for Setting the DTC

P0719

The TCM detects an open or short to ground on the stop lamp switch signal circuit during 8 consecutive vehicle accelerations.

P0724

The TCM detects the brake switch circuit is open during accelerations.

Action Taken When the DTC Sets

DTC P0719 and P0724 are Type C DTCs.

Conditions for Clearing the DTC

DTC P0719 and P0724 are Type C DTCs.

Diagnostic Aids

* Inspect the brake switch for proper mounting and operation.
* Inspect for ABS DTCs. A faulty ABS condition may contribute to setting DTC P0724.
* It may be necessary to also clear this DTC from the engine control module (ECM).

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Transmission General Information (Transmission General Information)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Transmission Control Module Scan Tool Information (Transmission Control Module Scan Tool Information)
Special Tools

J 35616 GM-Approved Terminal Test Kit

Circuit/System Verification

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

Circuit/System Testing

1. Install a scan tool. Turn ON the ignition, leaving the engine OFF. Observe the Brake Switch parameter. The parameter should display RELEASED.

• If the scan tool displays APPLIED, disconnect the stop lamp switch connector.

2. Observe the Brake Switch parameter on the scan tool with the stop lamp switch connector disconnected. The parameter should display APPLIED.

• If the scan tool displays RELEASED after the stop lamp switch connector disconnected, test the stop lamp switch.

• If the scan tool displays APPLIED after the stop lamp switch connector is disconnected, test the stop lamp switch signal circuit for a short to voltage.

3. While observing the brake switch parameter on the scan tool, use the J 35616 GM-approved terminal test kit and install a fused jumper wire between the ignition 1 voltage circuit and the stop lamp switch signal circuit. The brake switch parameter should change from RELEASED to APPLIED when the fused jumper wire is installed.

• If the brake switch parameter changes, replace the stop lamp switch.

4. Inspect the STOP LPS fuse; refer to Circuit Protection - Fuses (Component Tests and General Diagnostics) . The fuse should not be blown.

• If the fuse is blown, test the ignition 1 voltage circuit and the stop lamp switch signal circuit for a short to ground.

5. 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.

• If the voltage is not near the specified voltage, test the ignition voltage circuit for an open or high resistance.

6. Using the J 35616 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.

• 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. 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 (Verification Tests) after completing the repair.

* Vehicle Speed Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming.
* Stop Lamp Switch Replacement (Service and Repair)