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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 998 (Horn System) >> Diagnostic Information and Procedures >> Horns Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, connect a test lamp between the HORN fuse test point and ground.
  2. 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 below.
  3. 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.
  4. 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 below.
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