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I have a 1993 and the horn quit working. It is not the fuse and I doubt it is switches or the horns themselves which leads me to a horn relay. I removed the panal under the passanger's side dash and could not locate any relays. Where is the horn relay located on this car?
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by Richard Jinderlee
I have a 1993 and the horn quit working. It is not the fuse and I doubt it is switches or the horns themselves which leads me to a horn relay. I removed the panal under the passanger's side dash and could not locate any relays. Where is the horn relay located on this car?
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by Richard Jinderlee
I have a 1993 and the horn quit working. It is not the fuse and I doubt it is switches or the horns themselves which leads me to a horn relay. I removed the panal under the passanger's side dash and could not locate any relays. Where is the horn relay located on this car?
After closer inspection, I did find 5 relays under the passanger side dash. I did check the horn to see if the plug was getting a signal and it wasn't. The relays are in two groups, three toward the driver's side and two further toward the passanger side. Which one is the horn relay? Also, how might I set off the car alarm? This could help tell me which component was at fault.
here is the relay drawing from my 92 FSM should be the same for you
If you put the windows down and lock the car then reach in and try to unlock and open the door it should set the alarm off.
But why don't you think it's the switches? That was my problem (same setup as you have). They can oxidize creating a resistance to creating the ground
The alarm went off so it can't be the horns. There is no voltage getting to the horn switch. Also, I ran a hot lead from the cig lighter to the horn switch center contact and it blew the 15 amp fuse. I found with my ohm meter that the center contact is grounded. When the alarm is actuated, does it go through the horn relay or is it a seperate circuit? Could this be a defective relay? Could the problem be inside the steering wheel?
The alarm went off so it can't be the horns. There is no voltage getting to the horn switch. Also, I ran a hot lead from the cig lighter to the horn switch center contact and it blew the 15 amp fuse. I found with my ohm meter that the center contact is grounded. When the alarm is actuated, does it go through the horn relay or is it a seperate circuit? Could this be a defective relay? Could the problem be inside the steering wheel?
Lots of 'could be' - Brian had some very good suggestions. If you feel a relay issue just confirm part # match of the adjacent relays and swap them.
OP, Lets go through this. The horn buttons supply ground to the relay not 12v. 12v from the fuse goes to the relay pins 1 and 5 at all times. When either horn switch is pressed or CCM commands it a ground is applied to pin 2. When the ground is present 12v passes from pin 2 to pin 4 and on to the horns.
Since the horns activated with the alarm the realy, horns and wiring in between is working. SO now it's down to a few things. Switches, wiring between steering wheel and relay, weak spring on the contact, dirty turn signal canceling cam (it has the slip ring for the horn).
This is the circuit
At this pint I would attack in the folowing order.
Remove airbag (it will make this much easier) It is possible to get the plastic buttons out with it in place but it can result in breaking them and then your hunting used ones.
Clean the contacts and see if that fixes the problem. also check the wires. You can jumper the brass bar to either round contact to check the circuit.
If that doesn't work, then your looking at removing the steering wheel. here are some picks from mine.
Last edited by belairbrian; May 21, 2021 at 10:55 PM.
It looks to me that when pin 2 is grounded by either the horn switch or the CCM, the relay coil is activated and 12v passes from pin 1 to pin 4 to the horns. If pin 5 is hot, even though it passes thru the relay coil, shouldn't pin 2 read 12v and subsequently at the horn switch? And if so, and there is no continuity btetween pin 2 and the horn switch there must be a break somewhere between them. If the car alarm activates,shouldn't this indicate there is nothing wrong with the relay?
As I said last night, the relay is good.
40 years ago this summer, I was at Lowry AFB learning basic electronics from an old and very wise instructor. (By old I mean my age now). When we got to the part where we started troubleshooting circuits, the first piece of advice he gave us was break circuits in half. It cuts down on the time it takes to find the problem.
When you set of the alarm essentially you did just that. The relay to horn part of the circuit is good. The part that applies ground to the relay when the switches are pressed is bad.
Quit worrying about voltage, it is not relevant. And goign down the rabbit hole of inductive resistive circuits isn't going to fix the car.
So following the process of splitting the circuit, ideally you would now split the first half of the circuit again. The turn signal cam.
If you have the steering wheel off, jumper the horn contact to a known good ground, if the horn blows the problem is from the cam to the switches to ground.
If the wheel is still on, but Airbag removed, remove the spring loaded wire and place either a long narrow probe or a small screw driver in the hole. Jumper that to ground, the results of that will provide essentially the same answer.
Keep following that method and you will have the problem solved.
Last edited by belairbrian; May 22, 2021 at 04:53 PM.
If the 1993 has the horn embedded into the steering wheel as opposed to the 92's which have the plastic horn buttons on the steering wheel, it's likely that your contacts have disintegrated and you will likely need to replace the contacts.
If the 1993 has the horn embedded into the steering wheel as opposed to the 92's which have the plastic horn buttons on the steering wheel, it's likely that your contacts have disintegrated and you will likely need to replace the contacts.
90-93 use the same steering wheel, There are some small cosmetic differences like 90-91 have gray horn buttons.
The new wheel was introduced in 94.
Last edited by belairbrian; May 22, 2021 at 08:24 PM.
Hi:
Chances are it is a switch in the steering wheel, or the spring loaded plunger that makes contact with the slip ring on the backside of the steering wheel. There is a bayonet style fitting, and the tang breaks inside of the steering wheel hub, and the spring pressure to provide contact pressure on the slip ring goes away, and you have no electrical path for your horns.
The horns working when your alarm is set, indicates that most of the horn circuit is working. The alarm goes through a different relay. It is hard to diagnose issues away from the car, but I'm 99% sure it is in your steering wheel. I just had these failures with a 22K mile car.
I've got a youtube video talking about switches, and the bayonet fitting failure, and how to fix.
Best of luck.
Last edited by playzwithcars; May 22, 2021 at 08:45 PM.
With a great deal of help from everyone who replied to this thread, I found the problem. It turns out that It was the EXACT failure that plazwithcars experienced in his YouTube video- a broken plastic bayonet fitting. Thank you all for your help. Now all that I need is one of those most cleverly designed parts that plazwithcars made.
Or you could go to autozone, borrow the lock plate tool and puller (free under their loan-a-tool program), spend $6.50 on the part you need and fix it correctly.
horn not working
