Circuit/System Testing
WARNING: This page is about a different car, the 2011 GMC Acadia, 2011 Chevrolet Traverse, and 2011 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the HORN relay.
- Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 85 and ground
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuit terminal 87 for a short to ground. If all circuits test normal, test or replace the HORN relay.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- Command the horns ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM
- If all circuits test normal, test or replace the HORN relay.