GM Service Manual Online
For 1990-2009 cars only
    • Perform the following inspections if a poor horn tone is evident:
       - Ensure that the horn bolts in the mounting area are properly tightened.
       - Inspect for poor connections. Correct the poor connections if evident.
       - Inspect the ground connections. Correct the poor ground connections if evident.
    • Perform the following steps if a low-pitch moan (mooing sound) is evident:
       - The current is too high if a low-pitch moan (mooing sound) is evident.
       - Do not attempt to adjust the current. Remove the faulty horn assembly and replace it.
    • Perform the following inspection if a weak, strained tone is evident:
       - Inspect for a foreign object(s) in the horns.
       - Remove any foreign object(s) found in the horns.
    • Perform the following inspection if a harsh vibration is evident:
       - Ensure that the horn is not touching another object.
       - Bend or replace the horn bracket, if necessary, so the horn does not touch any other object.