GM Service Manual Online
For 1990-2009 cars only

Important: The following steps must be completed before using the symptom tables:

  1. Perform Diagnostic System Check - Vehicle in Vehicle DTC Information before using the symptom tables in order to verify that all of the following are true:
  2. • There are no DTCs set.
    • The control module(s) can communicate via the serial data link.
  3. Review the system operation in order to familiarize yourself with the system functions. Refer to Horns System Description and Operation .

Visual/Physical Inspection

    • 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 for obvious damage or conditions which could cause the symptom.
    • Inspect for debris in the joint where the horns fasten 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).

Intermittent

Faulty electrical connections or wiring may 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 the symptom:

    •  Horns Always On
    •  Horns Inoperative
    •  Horns Inoperative - One Horn
    •  Horns - Poor Tone