6L50/6L80/6L90 - Automatic Transmission
DTC P0719 or P0724
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/System Description
The brake switch indicates brake pedal status to the control solenoid (w/body and TCM) valve assembly. 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
DTC P0719
* No OSS DTCs P0722 or P0723.
* DTC P0719 has not passed this ignition cycle.
DTC P0724
* No OSS DTCs P0722 or P0723.
* DTC P0724 has not passed this ignition cycle.
Conditions for Setting the DTC
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 less than 8 km/h (5 mph) for 2 seconds;
* then, 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.
DTC 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 (Electrical Diagrams)
Connector End View Reference
* Electrical Center Identification Views
* Component Connector End Views
* Splice Pack Connector End Views
* Inline Harness Connector End Views
Electrical Information Reference
* Circuit Protection - Fuses
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
Scan Tool Reference
* Scan Tool Output Controls (Scan Tool Output Controls)
* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)
DTC Type Reference
* Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
* Diagnostic Trouble Code (DTC) List/Type (Diagnostic Trouble Code Descriptions)
Special Tools Required
J 35616 GM-Approved Terminal Test Kit
Circuit/System Verification
Start the engine. With the vehicle in Park, 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 terminal test kit and install a fused jumper wire between the stop lamp 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 lamp fuse; refer to Circuit Protection - Fuses . The fuse should not be blown.
• If the fuse is blown, test the voltage circuit and the stop lamp switch signal circuit for a short to ground.
5. Using a DMM, measure the voltage between the 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 voltage circuit for an open or high resistance.
6. Using the J 35616 GM terminal test kit measure the resistance of the stop lamp switch signal circuit between the TCM 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 control solenoid (w/body and TCM) valve assembly.
Component Testing
Inspect the stop lamp switch for proper adjustment; refer to Stop Lamp Switch Adjustment. With the stop lamp switch removed, use a DMM to measure to resistance across the pins for the 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.
* Control solenoid (w/body and TCM) valve assembly - refer to Control Module References for replacement, setup, and programming
* Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Control Solenoid Valve and Transmission Control Module Assembly Inspection) .
* Stop Lamp Switch Adjustment
* Stop Lamp Switch Replacement (Non-Adjustable Pedal) Stop Lamp Switch Replacement (Adjustable Pedal)