How to Troubleshoot the Horn on a Chevy Tahoeby Don Bowman
The horn on a Chevy Tahoe operates with the use of a relay. This means that the power for the horn is received from the fuse block under the hood. Power from the fuse block runs to the horn relay. The commonly open end of the wire goes to the horn. The horn is then grounded to the frame. Power to the activating terminal of the relay comes from the Body Ride Control or from the accessory side of the ignition switch. The negative side of the relay runs through the column to the clockspring. The clockspring is also used for the air bag system. The wire then continues to the steering wheel air bag where it is attached. As the air bag is pressed, it causes the wire to ground, actuating the relay which, in turn, activates the horn.
Lift the hood and remove the cover on the fuse relay box on the fenderwell. The quickest way to determine the problem area is to check the horn relay for operation. Turn the ignition key on and have a helper press the horn while placing a hand on the horn relay. Every time the horn switch or pad is depressed, the relay should make an audible click and can be felt activating. If the horn relay is activating, the horn itself should be checked. If the relay fails to operate, the fuse should be checked, and from there the ground in the steering wheel air bag needs to be checked.
Check the horn for power when the horn is activated. Pull the connector off the horn and probe the connector with a voltmeter. Probe the connector with the red lead from the voltmeter and ground the black lead. Have a helper press the horn and watch for power as the horn is depressed. If power is present, the horn is defective and needs to be replaced. If there is no power present, the problem is with the wiring from the relay to the horn.
Check the horn switch to see if it is making good contact with a ground. Disconnect the negative battery cable and wait 15 minutes for the circuits to go to sleep before continuing.
Remove the air bag by unscrewing the two Allen head screws in the back of the steering column. Lift the air bag gently and disconnect the two horn ground wires attached to the air bag. Detach the clockspring multiple wire connector to the air bag and lay the air bag on the seat.
Connect the negative cable on the battery. Turn the ignition key on and touch one of the two black horn ground wires to the steering post. If the horn blows, the problem is with the air bag or connection. If the horn does not blow, the problem is a bad clockspring. The clockspring will need to be replaced.
Things You'll Need
- Set of Allen head screwdrivers
- Set of wrenches
- Handle the air bag carefully as the slightest static from your body could set the air bag off.
Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).