Circuit/System Testing
- Ignition OFF, disconnect the X4 harness connector at the underhood fuse block.
- Connect a test lamp between the control circuit terminal G1 and B+.
- Press and release the horn switch. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground or a sticking horn switch. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to voltage, an open high resistance, or a horn switch which is not closing. If the circuit tests normal, replace the BCM.
- If all circuits test normal, replace the underhood fuse block.