Circuit/System Testing
WARNING: This page is about a different car, the 2010 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the X1 (LF1) or X2 (LAU) harness connector at the K20 ECM.
- Connect a test lamp between the signal circuit terminal listed below and ground:
- Terminal 57 (LF1)
- Terminal 52 (LAU)
- Ignition ON, observe the function of the test lamp while pressing and releasing the brake pedal. The test lamp should turn ON when the brake pedal is pressed and turn OFF when the brake pedal is released.
- If the test lamp is always ON, test the signal circuit for a short to voltage.
- If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance.
- If all circuits test normal, replace the K9 BCM.