Test Description
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 4: Tests if ground is constantly being applied to the horn relay.
- 5: The horn relay control circuit includes the horn switch. The horn switch must be tested for a short to ground when testing the relay control circuit.
Horns Always On
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Horns Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Horns |
| 2 |
|
Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
| 3 |
|
Go to Step 8 | Go to Step 4 |
| 4 | Connect a test lamp between the battery positive voltage circuit of the horn relay coil and the horn relay control circuit. Does the test lamp illuminate? |
Go to Step 5 | Go to Step 6 |
| 5 |
IMPORTANT:
The horn switch is part of the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement
in SIR. To disable the SIR system, refer to SIR Disabling and Enabling Zone 3
in SIR. Test the horn relay control circuit for a short to ground. The horn relay control circuit includes the horn switch. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems.Did you find and correct the condition? |
Go to Step 11 | Go to Step 7 |
| 6 | Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 11 | Go to Step 9 |
| 7 | Inspect for poor connections at the body control module. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 11 | Go to Step 10 |
| 8 | Repair the short to voltage in the horn control circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you complete the repair? |
Go to Step 11 | - |
| 9 | Replace the horn relay. Did you complete the replacement? |
Go to Step 11 | - |
| 10 |
IMPORTANT:
Perform the BCM programming procedure when replacing the BCM. Replace the BCM. Refer to Body Control Module Replacement
in Body Control System.Did you complete the replacement? |
Go to Step 11 | - |
| 11 | Operate the horn. Do the horns operate properly? |
System OK | Go to Step 1 |