jsmcol

Group, I need help to locate the horn switches for my 93 40th car that I got about two months ago. Having no horn has almost gotten me killed! This seems to be a magnet for people trying to run into me, so I've got to get the horn working again.


My security system works, just not off the buttons on the steering wheel, so I am assuming the issue is the individual switches behind the buttons. I've read a bunch of the threads, but have had a hard time locating the actual switches to fix it. Can anyone point me to a vendor or individual that may have the switches to sell?


I think if I can find the switches, I can do the work. The knowledge that has been imparted here by all of you that are more experienced is just unbelievable. To those that continue to answer questions by those of us that don't feel as secure fixing/ tearing things up, but then we read what you have done, or tell us how to fix something, all I can say is THANK YOU! You guys are great!


Jim

Wildride

Usually not the the switches. The buttons being plastic often break internally (there is a little plastic "post" about 1/8" in diameter that breaks off). I haven't tried to buy new buttons in years but they sometimes show up on e-Bay.

Another possibility is the bayonet connection on the wire that leads from the switches to the internals of the steering hub. It is plastic and also sometimes fails with age.

Got to love living in the "plastic" age. The stuff has a finite life.

jsmcol

Thanks Wild, guess I'll have to take it apart first to troubleshoot. I was hoping to have parts available and only take it apart once, but you are right, it could be several things.

Buick350X

In the same boat with Vette and Firebird, haven't taken Vette wheel apart yet to know but was considering the use of a tiny push button micro switch. And air horns

jsmcol

that's a solution, but I'm one of those crazy purists, I like it to look like it was from the factory. Now, if parts are no longer available, then we have to figure out a "work-around". it's tax time, but hopefully can get to this soon. Drove the car today! Can't wait for Spring...

Wildride

I wrote this up at least 15 years ago but the thread no longer seems to be 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 (2001 price). 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.Wait at least 15 minutes for any residual voltage stored in capacitors to bleed off) At the rear of the steering wheel spokes are embedded 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. (the male bayonet may be available at an electronics suppler).

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

antfarmer2

https://www.oempartsource.com/oe-gm/...URIaAj6K8P8HAQ

jsmcol

Thanks for that, I had already contacted them and tried ordering the part #2 on the diagram, thinking I needed the contact, not the button, and they were no longer available. There are a few people that sell the button on ebay, so if it comes to that, at least that part is around. Again, will have to take it apart to really find out what it is.
Thanks so much for taking the time to answer.
I'll post what I find once apart so maybe to help others...

jsmcol

So I checked to be sure the alarm system was working properly, it is.


I also pulled the horn buttons off by sliding them out without pulling the cover off the wheel (Thanks Wildride, didn't know they would come off without taking it all apart). The nipples are still on the buttons, they look like they function properly. When I push down on the brass contacts (which I also took apart to make sure the little nipple was on the backside of those and would make contact if pushed) then no horn, like it should.


So, I assume the next step is to take the wheel apart and see if the horn switch is bad? That was my original post, where can we get the switches?? Does anyone know if they are being made?? GM parts doesn't have them, tried to buy one that they said they have, and they cancelled the order- no longer available...


I need to make my horn work!! Any help would be appreciated. Can the switch be repaired? Anyone ever try that?


Jim

belairbrian

You lost me here. If you removed the plastic horn buttons on either side of the airbag and got to the copper switches you have reached the "switches". When the contacts are pressed together, a ground is applied to the horn relay through the horn lead wire and the horn ring on the turn cancelling cam.

If pressing the contacts doesn't activate the horns, then its the wiring the spring loaded contact in the wheel or the ring on the cam.

I have mine apart right now. The tube on my cam was broken so it wasn't holding the spring loaded contact in place

belairbrian

here's what you will find with the airbag and clock spring out of the way

jsmcol

With everything I've read, everyone kept saying the "switches needed to be replaced, which I assume were connected to the copper pieces that make contact. If that isn't the case, then it must be the same thing as yours. Time to pull the wheel...


Thanks for the help and the picture.

belairbrian

Standby my left was intermittent so I took the wheel to my electronics bench I think I found the problem and will post pics shortly

belairbrian

I found what was causing my horn button to intermittently work.

While this can be done with the airbag in, i recommend removing it. Much better access to the button lock tabs/hooks and it takes all of ten minutes to remove. First remove the plastic buttons and inspect the nubs if they are broken find new buttons. If they are good continue as below.





i took the horn to the bench and tested it since I had it off since I was working on the turn signals as well

by connecting my DVM, in OHMs mode, i could test the buttons
If testing on the car press in gently on the horn wire retainer, turn ccw and remove the wire.



I took the buttons apart and found corrosion, it actually looked like a light carbon build up,
both the tiny contacts on the copper flex plates and the ones from the wheel frame were bad. When you first take the plastic off, it looks like the copper touching the brass completes the circuit. It DOESN'T.

The contact occurs when the tiny silver buttons on the copper flex plate touch the frame of the steering wheel The brass to copper contact connects both flex plates to the wire

mark970

holy smokes there's some great info on this thread...i have a question slightly off topic but still horn related.

On a 1995 PKE system, is there a way to disable the "Chirp"? its rather annoying and i live in a town home community and i work nights. i do like the passive locking/unlocking system but if there was a way to stop communication to the horn via the PKE system and keep the normal horn function, i would LOVE to do that.

belairbrian

Don't know if the PKE system can be programmed for different modes of arming or not. I can on my Toyota MR2. Also, I only have diagrams for my 92 but wonder if your 95 chirps the horn the same way. On a 92 the CCM applies a temporary ground to the horn relay. There are 2 ground wires to the horn relay. One from the steering wheel and one from the CCM. Looking at a wiring diagram for a 95 I found in another thread it appears the 95 works the same way. However this approach would also disable the horn if the alarm was tripped.

mark970

THAT sir is exactly what i'm looking for!!
yeah you cant program the chirp to be off for that generation so i was hoping for a work-around. pure brilliance!!!

thanks again, i will def give that a look

belairbrian

note that would also disable the horn if the alarm was tripped.

mark970

booooooo!!!!!

jsmcol

[QUOTE=Wildride;1594409488]

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. (the male bayonet may be available at an electronics suppler).

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.




Wild, you are a genius! I finally got a chance to take the airbag out and look at what you call the "bayonet", which in my case was no longer being held in place by the white plastic retaining ring. I made a piece like you said, cutting up and old CD, using a scroll saw and cutting a slot into it for the wire to go through, but not the black plastic retaining piece. Cut it down to size to allow it to bolt into both the steering wheel puller holes. Put it all back together and the horns worked!! I CAN USE MY HORN AGAIN !!
(Life's simple pleasures...) Anyway, thanks again, you may have saved my life by keeping someone from hitting me.


Anyone that has tried everything else, it could be this. The white plastic retaining ring fell apart into pieces as I pulled out the airbag, so nothing was keeping the two components of the horn wiring together. If you go to all this trouble, be sure to clean off both ends of the wires just to be sure they make a good contact. May also want to clean the switch contacts under the horn buttons as well. In my case, all were good, but I could see where they may become corroded and not work well.


Jim