For 1990-2009 cars

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. Tests if ground is constantly being applied to the horn relay .

2. The horn relay control circuit includes the horn slip. The horn slip ring and the horn switch must be tested for a short to ground when testing the relay control circuit.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check-Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Is the vehicle equipped with keyless entry? | -- | Go to Step 3 | Go to Step 4
3 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the Body Control Module Horn Output ON and OFF.

Is the horn ON at all times?

--

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections

4 |

1. Turn OFF the ignition.
2. Disconnect the horn relay.

Does the horn operate?

--

Go to Step 9

Go to Step 5

5 | 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 6 | Go to Step 7
6 | Test the horn relay control circuit for a short to ground. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8
7 | Inspect for poor connections at the horn relay. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10
8 | Inspect for poor connections at the body control module (BCM). Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11
9 | Repair the short to voltage in the horn control circuit. Did you complete the repair? | -- | Go to Step 12 | --
10 | Replace the horn relay. Did you complete the replacement? | -- | Go to Step 12 | --
11 | Important: Perform the BCM programming procedure when replacing the BCM. Replace the BCM. Refer to Control Module References Does the test lamp illuminate? | -- | Go to Step 12 | --
12 | Operate the horn. Does the horn operate properly? | -- | System OK | Go to Step 1