4T45-E Automatic Transaxle

DTC P0719 or P0724

DTC Descriptor
This diagnostic procedure supports the following DTCs:
^ DTC P0719 Brake Switch Circuit Low Voltage
^ DTC P0724 Brake Switch Circuit High Voltage

Diagnostic Fault Information

Important:
Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview








Circuit/System Description
The brake switch indicates brake pedal status to the transmission control module (TCM). The normally-closed brake switch supplies a Closed status to the TCM from the Body Control Module (BCM). Applying the brake pedal opens the switch, interrupts voltage to the BCM. Releasing the brake pedal supplies voltage to the BCM. When the BCM senses 0 volts at the brake switch input, the BCM sends a signal to the TCM to de-energize the torque converter clutch (TCC) solenoid valve.

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 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.

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

DTC Type Reference
^ Diagnostic Trouble Code (DTC) Type Definitions
^ Diagnostic Trouble Code (DTC) List/Type

^ Special Tools Required
- J 35616 GM Terminal Test Kit

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. If the scan tool displays Open, disconnect the stop lamp switch connector.
2. Observe the TCC Brake Switch parameter on the scan tool with the stop lamp switch connector disconnected. The parameter should display Open. 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.
3. While observing the TCC brake switch parameter on the scan tool, use the J 35616 GM 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. If the TCC brake switch parameter changes, replace the Stop Lamp Switch.
4. Inspect the STOP LPS fuse; refer to Circuit Protection - Fuses. 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 1 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 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.
7. 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 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

Important:
Always perform the Diagnostic Repair Verification after completing the repair. Verification Tests

Output Speed Sensor Replacement

Control Module References for BCM replacement, setup, and programming

Stop Lamp Switch Adjustment

Stop Lamp Switch Replacement