For 1990-2009 cars

Important Preliminary Checks Before Starting: Perform Diagnostic System Check - Horns before using the symptom tables in order to verify that all of the following are true:

1. There are no DTCs set.
2. The body control module (BCM) can communicate via the serial data link.

Review the system operation in order to familiarize yourself with the system functions. Refer to Horns Operation .

### Visual/Physical Inspection

Several of the symptom procedures ask for a careful visual/physical check. This step is extremely important-it could lead to correcting a problem without further checks and can save valuable time. These checks include the following:

• | Inspect for aftermarket devices which could affect the operation of the Horn System. Refer to Checking Aftermarket Accessories in Wiring Systems.

• | Inspect the easily accessible or visible system components and harness connectors for obvious damage or conditions which could cause the symptom.

• | Perform the following if the horn buzzes or has a harsh tone:

• | Inspect for debris in the joint where the horn fastens to the vehicle.

• | Test the torque of the horn mounting hardware. The horn mounting hardware should be tightened to a torque of 10 N·m (7 lb-ft).

### Intermittents

Important: Faulty electrical connections or wiring may also be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

### Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose a symptom that does not set a DTC:

• | Horns Always On

• | Horns Inoperative

• | Horns - Poor Tone