Circuit/System Verification
- Vehicle OFF, disconnect the X1 harness connector as the ECM.
- Connect a test lamp between the control circuit terminal 33 and ground.
- Vehicle in Service Mode, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If all test normal, replace the ECM.