Hello All,

I own a 1990 vette with a horn that will not work when pressed at the steering wheel, but will work with the stock theft deterent system. Before I start dismantling the interior, I am hoping someone can give me the heads up on what to check first . To my knowledge , I believe the interior is stock but I can't say for sure . She was preowned when I purchased her and the horn has never worked since I've owned the car approx. 2 years.

Any help will be much appreciated. Thanks in advance.

 

I wrote this up several years ago but the thread is no longer in the archives. Maybe it will help you.

Apparently horn problems are very common on the C-4 and in particular with the 1990. There have been many posts on the subject over the years.

I will try to walk you through this, but it is being done from memory so please bear with me. What is mentioned here is mainly specific to the 1990 or later C-4. Prior to 1990 a different design was used.

I am assuming that you have checked and cleaned the electrical connections at the horns themselves and checked the fuses.

Many people have reported corrosion in the horns themselves. The cure is either replacement or squirting penetrating oil or WD-40 into the horn. I have never had to try that so I can’t vouch for its effectiveness.

The operation of the horn relay can be checked with 98% reliability by following these steps:

1. Roll down the windows.
2. Turn the ignition “Off”.
3. Exit the car.
4. Lock the doors.
5. Reach in through the window and “Unlock the Door”
6. Attempt to start the car.

If when you try to start the car and the horn goes off, the horn relay is okay. To reset the alarm and to be able to start the car, lock the door with the key and then unlock it with the key. The horn relay is a DPST relay that works either from the horn buttons or the security system.

There are several problems I have found that seem to come up with the horn buttons,

1. The Buttons themselves are made of a plastic that seems to deteriorate over time. This plus the normal (and abnormal) pressing on the buttons causes a little "nipple" inside of them to break. This nipple's purpose is to press down on the brass contacts underneath it and complete the circuit. No nipple = no contact = no horn.
2. There is a wire (one only) that goes between the brass contacts and the hub of the steering wheel. At the end of this wire is attached a plastic spring loaded male bayonet fitting that is inserted into a female socket in the steering wheel hub and twisted into place to hold it. This plastic bayonet fitting and/or its socket will also give up after time and separate causing an intermittent contact or no contact.

Solutions:

1. The horn buttons are available from GM for about $6.95 each. PN
12506007 and 12500608. There are two ways to remove them from the steering wheel.

A. Using a dull thin blade slide it along the hub side of the button feeling carefully for the catch that latches the button to the wheel. There are two on each side-total four, you only have to find and release two on one side of the button.

The top one is about 1/2-3/4' down from the top of the button and the bottom one is about 1/2-3/4" up from the bottom of the button. When you locate each catch, push in (toward the center of the button) gently on it while lifting the button. You have to do this twice-top and bottom on one side. The button should then pop off.
I have mine discretely marked so the catches are easy to find. You may want to do this to them after they are off.

B. The second way means removing the airbag. Disconnect the battery. Pull the fuse controlling the airbag. At the rear of the steering wheel spokes are imbeded two torx screws (size T-27 ). Unscrew these two screws and then GENTLY lift off the airbag. I advise being off to one side of the steering wheel while doing this as an improperly handled airbag can be dangerous. (These things are shipped all over the country without problem but I would rather be cautious). BE SURE THERE IS NO ELECTRICAL POWER AVAILABLE!!!!
After the airbag is removed, the buttons, contacts and wires are easily accessible.

2. If the wire/bayonet socket is defective the solution is a little more involved. The airbag must be removed as above to get to the wire.

To the best of my knowledge replacement sockets are not available and the GM solution is to replace the steering wheel hub assembly. VERY EXPENSIVE and a lot of labor.

But there is hope. Using a piece of stiff plastic (1/16" Plexiglas sheet works fine or cut up an old AOL CD) cut it into a U shaped piece that fits flat into the hub around the hub retaining bolt and with a very narrow slot that the horn wire was fed (but not wide enough slot to allow the bayonet socket to come through) over the socket. This piece will hold the bayonet socket in place. The plastic piece is held in place by a very short bolt (1/2") that is screwed into one of the bolt holes that are used for a steering wheel puller. DO NOT use a long bolt as it may hit the internals underneath the hub causing short or other problems.

I hope the description makes sense. A picture (if I had one) would make it very clear.

It seems that many people have problems with the horns on their C-4. I hope this helps resolve some of the problems.


References:

General Motors Corporation Parts and Illustration Catalog 1984-90 Chevrolet Y (Corvette)

General Motors Corporation 1990 Corvette Service Manual

Alldata Corporation

 

Thank You so much for taking the time to answer my query, in a most informative and educational response.
Be assured your time will not be wasted. I will make good use of the knowledge you have unselfishly supplied .

Thank You Again and Hopefully I maybe as gracious someday and help someone as you have here.

c4tonezone