m12462

Hi, I have a 1998 3.8L mustang convertible. I bought it 4 years ago at a great price with plans to replace the bad/non-working parts and give it to my son when he is old enough to drive. That time is quickly approaching.

I previously had an issue with the drivers electric seat not working and the great experts on this forum helped me, the novice, resolve that issue so I thought I would try again with a new issue.

The cars horn is not working. I quickly located the proper fuse based on the attached diagram and, it appeared to be intact but, just to be safe, I replaced it anyway...still no horn.

Besides a blown fuse, any ideas on what else might be the source of this issue and, if known, is it a "do-it-yourself" fix?



On a quick side note (without starting a new thread), I also noticed the turn signal is not working but it was a week ago...I just cant determine based on the attached fuse diagram, which fuse controls that function (or if's it's even fused based at all).

Thanks!

warthogdriver

If the fuse on the horn is good you could remove the airbag to check the connections on the horn switch. Its easy to do...disconnect battery...then pop the access covers on the sides of the trim under the airbag...remove the two bolts and carefully lift it out to see what the wiring undernesth looks like.
The turn signal could be the flasher relay...forgot proper name...its a short cylunder on the fuse block...do the hazards work?

petrock

According to my ’98 Factory wiring diagram there is a relay in the horn circuit, however, I can’t find it in any of the component location indexes. If you can find it on your ride, that is where I would start looking before tearing stuff apart. The whole for the relay’s pin 30 should have 12 volts all the time (even with the key out of the ignition). If not, backtrack towards the fuse to find the break in the circuit. The whole for pin 87 goes to the horn. If you take a small piece of wire and jump the wholes for pin 30 & pin 87, the horn should go off. If it doesn’t, then either there is a break in the circuit between the whole for pin 87 and the horn or both horns are bad. If the horn does go off, then the problem is somewhere on the coil side of the relay (pins 85 & 86). Diagnosing that side depends on if your car came stock with keyless entry, and/or anti-theft system.

If you can’t find the relay, then you can check for voltage at the horns themselves when pressing the horn button. The horns (high & low pitch) are inside the drivers side fender. Pull the fender well skirt and you should have pretty of access. Good luck...

Daehawk

I would be too scared to do anything around the airbag myself.

petrock

Its not that bad but I agree it can be a little nerve racking. Just make sure the battery is disconnected and you should be fine. Don’t put any part of your body within a foot of the face of the air bag. Treat it like a (un)loaded gun while working on the steering column and you should be fine.

m12462

Yes, the hazard lights do work.

BabyGT

I would like to ad that whenever messing with the airbag completely remove the battery and let the car sit for about 15 minutes at least to give the charge time to dissipate. The airbag can still go off a few minutes after the battery has been removed. This is to allow the airbag to function in an accident in the instance that somehow the battery becomes disconnected before it is triggered.

m12462

I wanted to revisit this issue once again as I had to step away from this project for several weeks. As I noted in my original post (above), I noticed the horn was not working. Since then, I have also noticed that the turn signals are not working. A few weeks before noticing the horn was not working, I had the Seats, the Center Console and all the Interior Kick Panels and the original carpet out of the car because I was installing new carpet. I also had a mechanic here doing some engine work. When he completed his work, we drove the car and the turn signals were definitely working then (we didn't test the horn). When he returned a few weeks later, I explained that the horn and turn signals were not working. After confirming, as I did, that the fuse in the box under the hood was fine (I still replaced it just to be sure), he checked another fuse panel under the dash (that I didn't even know existed...remember, I'm a complete novice here). He did find a 15 amp fuse that was blown (the fuses there are larger than the really small ones under the hood) but the fuse diagram (see below) don't show any connection to the horn or turn signals. His best guess is that, since the turn signals were working when he was there two weeks earlier, is that while I was installing the new carpet I must have somehow compromised (shorted or forgot to plug something back together) the cable that controls those functions (possibly piercing it or pinching or crimping it somehow). He suggested retracing my steps but that means basically re-stripping the entire interior, which is SO time-consuming.

The problem is that I don't even know what kind a cable I'm looking for, or if the horn and the turn signals are controlled by the same cable (I just made that assumption because they seemed to go out at the same time). Where does the cable originate? I don't wanted to pull out the back seats and rear kick panels if it originates from the console forward. Does it run to the battery or one of the two fuse locations? What color is the cable?

That's my dilemma and I'm hoping one of the knowledgeable experts on the forum can help me by either giving me an easier, more efficient way to correcting this issue or, if I have to pull everything out, answering the questions above so I will at least know what I'm looking for. Also, to answer a question above, yes, the hazards do work. Thanks so much for your time reading this post!

BabyGT

The horn and the signals are on separate circuits. Does your cruise control work? That's on the same circuit as the horn wiring.

No, none of the wiring for the horn runs past the dash, the signals on the other hand snake all through the car. Do your hazards work?

m12462

Yes, the hazards work. I need to go drive it to see if the cruise control works. Will post back on that. Thanks!