Circuit/System Testing
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.