Horn problems, 94 Ultra

padriver · #1 11-10-2009, 03:09 PM

The other day, there was this m*r*n in front of me so I was compelled to use my horn. Much to my surprise, nothing happened when I hit the center of the steering wheel.
So I checked the horn fuse in the relay center, and it was blown. I got a new one and when I inserted it, the horns sounded for a fraction of a second and the fuse blew again.

So obviously, there are two things wrong here:
First, the horns should not sound without touching the horn switch.
Second, the fuse should not blow when the horns sound.

I went ahead and removed the horn relay and checked it. It seems to be fine. Also, without the relay in place, the fuse did not blow.
Then I unplugged all four horns and inserted the relay again. The fuse did not blow.
I plugged in one horn and it sounded immediately, but the fuse did not blow.
I haven't checked each horn individually yet, but I guess one of them must be bad and cause a short circuit.
So far so good. That was the easy part.

Now, why do the horns sound without touching the horn button? My guess is that the switch in the steering wheel is bad somehow. I'd like to disassemble the wheel and take a look, but with the airbag and all, I'm a little hesitant.
And I did not find the horn switches as individual replacement part. Does that mean the entire airbag assembly needs to be replaced? Is it even possible to repair a horn switch?

Thanks for any information.

HotZ28 · #2 11-10-2009, 03:37 PM

Quote:

Originally Posted by padriver

Now, why do the horns sound without touching the horn button? My guess is that the switch in the steering wheel is bad somehow. I'd like to disassemble the wheel and take a look, but with the airbag and all, I'm a little hesitant.
And I did not find the horn switches as individual replacement part. Does that mean the entire airbag assembly needs to be replaced? Is it even possible to repair a horn switch?

Click Here for some alternatives.

padriver · #3 11-10-2009, 04:19 PM

HotZ28, that's great information, thanks!

So, there are two horn switches. I guess there is a chance that only one is bad and unplugging the bad one would solve my problem.

HotZ28 · #4 11-10-2009, 04:39 PM

Quote:

Originally Posted by padriver

HotZ28, that's great information, thanks!

So, there are two horn switches. I guess there is a chance that only one is bad and unplugging the bad one would solve my problem.

That is a possibility, but as the old saying goes "When one goes bad, the other is not far behind".

Just remember, when working in this area, be sure to disconnect the negative battery cable first, then the positive and touch the two together, in order to drain any residual power. BTW, you are correct, the switches are an integral part of the air bag assembly and they can not be replaced without replacing the whole unit.

padriver · #5 11-10-2009, 06:16 PM

Quote:

Originally Posted by HotZ28

That is a possibility, but as the old saying goes "When one goes bad, the other is not far behind".

Just remember, when working in this area, be sure to disconnect the negative battery cable first, then the positive and touch the two together, in order to drain any residual power. BTW, you are correct, the switches are an integral part of the air bag assembly and they can not be replaced without replacing the whole unit.

I hope that one of the switches still works fine and I can save the idea of drilling a hole and mounting a button for later...

I'll keep posting any updates.

padriver · #6 06-05-2011, 04:19 PM

It's been awhile, but I promised an update, so here it is:

I removed the airbag and checked the two horn contacts, and sure enough, one of them is bad. I unhooked the bad one and now nothing happens when the horn fuse is inserted, just as it should be. Only when I press the horn switch, the fuse still blows, as expected...

But all I have to do now is find the bad horn and replace it, at least that's what I hope.

HotZ28 · #7 06-06-2011, 12:28 AM

The horns are sorta hidden behind the left/right fender-wells & hard to find, but the wiring is easily accessible. Good luck, I hope you find the problem.

TopherS · #8 06-07-2011, 12:17 AM

padriver - when you say you inspected the horn contacts and that one of them is bad...how did it look?

I have a problem where my horn just honks by itself every so often...just a quick 1-second honk...but always seems to be when I'm sitting at a red light and everyone around me thinks I'm being quite rude.

I've taken out my horn's fuse to avoid any further "incidents", but would like to see if I can get the problem fixed. I haven't gotten up the courage to take out the airbag yet, but when I do, I don't know what I'd be looking for...

padriver · #9 06-07-2011, 12:24 PM

@ TopherS:

The contacts themselves are not directly accessible, so you cannot inspect them visually. Unless of course you are bold enough to try and disassemble the airbag module, which I do not recommend...

I used an ohmmeter to check the resistance. I unhooked the two leads that are going into the steering column and measured the resistance. It was 0 ohms, as expected with a bad contact. It should be open circuit with no horn switches pressed.
The two horn switches are wired in parallel and can be unhooked individually. So I unplugged the left one and measured the resistance again: Now it reads infinite, which is OK. I found the bad switch.

Well, I myself was also pretty reluctant to play around with the airbag. I unhooked the battery over night and performed the official procedure for disabling the airbag (remove the fuse and unplug the yellow airbag connector), to be absolutely sure. Everything went well, I'm still alive.

Here are two pics I took:
First one is the horn contact leads, second one is one of the two horn switch connectors.

TopherS · #10 06-09-2011, 12:15 PM

Awesome, padriver.

Thanks much for your info!

padriver · #11 06-13-2011, 03:25 PM

Today I checked the horns.
Measuring the resistance turned out to be difficult without removing the horns because it's impossible to access the connectors with an ohmmeter, there's just no room.

So I did the try-and-error approach and I identified the faulty horn: The one on the passenger side, closer to the front (my car has the four horn option so I got two on each side). If I unplug this horn, the other three work as they should, no more fuse blowing!

Now, I need to find out which note the defective horn is. The service manual says it's either the C note or the A note. I hope it's not the C note because this one seems to be no longer available... I didn't find it in the online parts catalogs.

padriver · #12 07-28-2011, 01:02 PM

Guys, it is the C note horn...

What do?

ZiggyPA · #13 07-28-2011, 02:34 PM

I can't imagine that you wouldn't be able to find the right horn (well maybe not originally used on the PA but aftermarket or from another car brand, after all it's only a horn). Rockauto lists a dozen of different horns, but most are just labeled "high" or "low".
That doesn't say much, just as "A" or "C", depending on the octave one may be higher or lower than the other. Try to figure out the frequency, and you can most certainly find a matching horn somewhere.

padriver · #14 07-28-2011, 04:40 PM

Yeah, well, of course it would be no problem to find just a horn.
Call me crazy, but I want to keep my car all-original. Plus I don't want to disturb that signature train horn sound

(although I have to say, at the moment, with only three working horns, it still doesn't sound too bad).

I guess the easiest would be to visit a junkyard on my next trip to the US...

HotZ28 · #15 07-28-2011, 09:11 PM

IIRC the 4-note horn includes A,C,D & F notes and the C & D notes are on the right side. I am not sure which is front or back, so I would order both (or all). This is the same combination used on many Cadillac's, Buick's, Chevrolet's and Oldsmobile's with the 4-note horn option. Check eBay for availability. Click Here

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