When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I did a little searching and didn't find any answers to my questions regarding horn relay location. When I bought the car a year ago, one side of the horn system worked. Since then the whole system has quit working. Using a voltmeter and checking the wiring at each horn, I can tell that no power goes to either horn. With the horns out of the car and connecting 12 volts to each horn off of another battery reveals that one horn is dead, and the other one works. I have the fsm and it gives a location for the horn relay as "below lower right hand side of instrument panel" So does this mean, remove the hush panel from the PASSENGER side and the relay will be there, or is it the right side of the DRIVER side? I am using the diagnostic flow chart on page 8A-40-2 that directs me to next investigate the horn relay. Any help on determining location will be helpful. Or any other horn advice as well! Thanks!
You should be able to hear the horn relays clicking when you press on the horn button(s).
If you hear the clicks then the problem is in the relays or wiring or horns.
If no clicks then the problem is in the horn button contacts or the wiring in the steering column.
The horn relay on early cars is behind the DIC in the center cluster. Later cars have them mounted on the inside of the firewall at the bottom of the steering column. [ EDIT ] See post #6 -- it appears I was wrong on this. [ /EDIT ]
Last edited by Cliff Harris; 07-22-2015 at 12:27 AM.
Reason: Corrected location of horn relays.
It's the plastic piece under the steering wheel they are notorious for falling apart, I took mine apart and was able to put a short screw in it to hold the wire in the hole.
It's been working fine now for the past few months.
You should be able to hear the horn relays clicking when you press on the horn button(s).
If you hear the clicks then the problem is in the relays or wiring or horns.
If no clicks then the problem is in the horn button contacts or the wiring in the steering column.
The horn relays on early cars are in the engine compartment. Later cars have them mounted on the inside of the firewall at the bottom of the steering column.
I have a 91 also. My horns would work sitting in the garage but when I backed out they would quit. After sitting in the garage awhile they would start working again, go figure. My problem was in the steering column. after taking off the airbag there is a wire that comes from the buttons and goes down into the column, it has a spring on it with a contact at the end. There is a plastic part that holds this wire and spring down in the column and sometimes it breaks and the wire backs out and loses contact. As mentioned in someone's earlier post he fixed his with a bolt to hold the spring and wire down. I fixed mine by cutting a music cd in half , drilling a hole to bolt it down and a slot to slide the wire through so the cd would hold the wire down. Horns work fine now. As for the relay location it is underneath the passenger side trim plate remove it and you will see a bank of relays up there in no mans land. Can't remember which one is the horn relay but your fsm will tell you. Hope all this helps.
It's the plastic piece under the steering wheel they are notorious for falling apart, I took mine apart and was able to put a short screw in it to hold the wire in the hole.
It's been working fine now for the past few months.
Thanks Bob and also tpfarm for your instruction regarding horn buttons. Last weekend, I did find the horn relay, and went ahead and replaced it. it just cost 12bucks anyway, but did not resolve the problem. I believe it is probably as you said, either the button switches or column wiring. I perhaps will get a chance to dive into it next weekend when home again. I have not checked, but imagine that the air bag will need to come off the steering wheel? The service manual says to pull the air bag fuse and also disconnect the yellow connector on the steering column. Are they both necessary, or is just pulling the fuse sufficient, and wait the 10 minutes?
I disabled the SIR system today and took the airbag off of the steering wheel. Easy to do, just two Torx screws on the front side of the wheel. Had it off in a jiffy. Then found that the horn wire that has the little spring on the end of it was no longer in its little nest. Just as Bob Guzzy and tpfarm had said in earlier posts, the small round white plastic piece that the spring wire inserts into had broken. I used a piece of 1/8 inch Plexiglas, a short M8 by 1.25 allen headed cap screw, and a short nylon spacer washer to secure the spring wire in its place. Here are a few pictures that should help anyone working on their steering wheel horn wiring.
This is the airbag removed from the steering wheel. Remember to disable the SIR system first!
This horn wire with a spring connection fits into a small round white plastic retainer, that was broken, no longer securing the connection
this is the loose end of the horn wiring connection. this little pin is retained in the white plastic part, that typically breaks
I made a new retainer out of a piece of Plexiglas. Use a M8 by 1.25 cap screw in a wheel puller hole to secure it. I needed about an eight inch spacer beneath it to make it all plane out
Here is the completed repair. It would have gone MUCH better, if a previous owner had not tried to pull the steering wheel using American thread screws in the puller holes!
The horns now work, but sound like a wounded goose. I will find some new ones.
I just had my 1991 back from a respray. They forgot to connect both hood lights - easy fix, I just plugged them. However, both horn buttons don't work. Both horns are connected.
If I recall they were both working fine before I sent the car out (car has been sitting in my garage since last June).
It does work when anti-theft engages.
I removed the air bag and tried to cheat around to get the horn buttons working, without any luck. I do not understand your fix. I do not exactly understand how it works. Is there something broken?
EDIT: I removed both horn buttons, played around a little bit... And now everything works fine. I do not understand why and I still do not get how that wire shown in the picture works.
Last edited by MuRCieLaGo; 04-17-2020 at 11:45 PM.
My 91 the horn wasn't working when I got the car. The previous owner said he never used it so he didn't know that it wasn't working. I watched a couple videos on YouTube. Turns out all I had to do was clean the contacts under the horn buttons. They pop right off but you have to be careful and not break them. It only took me a few minutes and I cleaned the horn contacts with the eraser on a pencil. That was about two years ago and the horn is still working just fine. Sometimes the plastic pin breaks off on the button and it no longer makes contact with the metal under the button. You can find new and used ones on ebay if needed.
HI. It has been along time since i worked on my horn. I sold the car five years ago. glad you got your horns working. IIRC the spring part must stay down and lock into the column, if it jumps out your horns will not work. If hey stop working again you must replace that part or do as I did and devise a way to keep it down so it makes contact.
Wow! I didn't even pay attention to how old the thread was, LOL. I liked working on cars without airbags. It was a lot easier pulling a wheel and working on the column.
Yeah , that was a blast from the past. I kept my 91 for seventeen years, i t was a great car. I just got worried about all the electronics going bad and sold it I will unsubscribe from this thread. My 73 is so much easier to work on . Enjoy your C4 .
Yeah , that was a blast from the past. I kept my 91 for seventeen years, i t was a great car. I just got worried about all the electronics going bad and sold it I will unsubscribe from this thread. My 73 is so much easier to work on . Enjoy your C4 .
Hey TP. Your knowledge is valuable, even if you no longer own a C4. Sold mine a year ago as well, but faintly remember the horn issue. Glad this thread got resurrected and glad it could help someone else. Steve
07-04-2013, 12:55 PM
1991 horn inoperative
