Circuit/System Testing
WARNING: This page is about a different car, the 2012 Buick Verano. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the X1 (LUW/LUJ) harness connector at the K20 ECM.
- Connect a test lamp between the appropriate signal circuit terminal listed below and ground.
- Terminal 25 (LUW)
- Terminal 33 (LUJ)
- Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
- If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
- If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
- If all circuits test normal, replace the K20 ECM.