Circuit/System Verification

WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, connect a test lamp between the horn fuse test point and ground.
Press and release the horn switch. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp does not illuminate or remains illuminated at all times, refer to Horn Switch Circuit Test .
Ignition ON, command the horn 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 does not illuminate, test the control circuit terminal 18 at the BCM for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
Connect a 15A fused jumper wire between the horn fuse test point and B+. The horn should sound and emit a clear and even tone.
- If the horn does not sound, refer to Horn Circuit Test .
- If the sound emitted is not clear and even, refer to Horn - Poor Tone .