Circuit/System Verification

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. 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 10A fused jumper wire between the HORN fused test point and B+. The horns 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 .