Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra and 2008 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- 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-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.
- 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.
- 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.
- 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.