Hey guys, I have been battling electrical problems on my 92 mustang 5.0 for some weeks now. the problem that i cant figure out now is why my horn is going off when i switch on the light switch! i also cant figure out why my wipers and parking lights dont work. I replaced the multi function switch, the light switch and the hazard switch as they where bad. HELP PLEASE!
Electrical Horns goes of when I switch on lights
- Thread starter Cwestcott22
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Here is a wiring diagram for the lights and radio from veryuseful.com:
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.gif
fuse box: http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
i have heard of this problem before but can't recall what was going on, crs you know.
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.gif
fuse box: http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
i have heard of this problem before but can't recall what was going on, crs you know.
Two things that I would do is pull the horn fuse out and first see if the horn blows when the lights are turned on, if not then stick a test light to the hot side of the fuse and see if it lights up when the lights are turned on.
i'm not sure what that would mean but I'll think of something unless someone chimes in.
i'm not sure what that would mean but I'll think of something unless someone chimes in.
I think not, you pulled the fuse and the horn still blows your likely getting some kind of feed back through the headlight circuit?
Did you just get the car or you've had it while and this just developed?
Did you just get the car or you've had it while and this just developed?
I have had the car about a month. I have been getting it ready for inspection as it drives well. Except, the constant horn when the lights are on, the windshield wipers don't work and the parking lights dont work.
You need a repair manual with wiring diagram, look for an assembly manual for your year, wiring colors changed for some years. Look on ebay,
have you looked to see if any wires have been hacked
have you looked to see if any wires have been hacked
Yikes. So, you likely have an alarm system installed. If you are not using it, carefully remove it. Find where wires were cut to splice in the alarm. Match up the wire colors and use heat sealed butt connectors to reconnect the original wires.
Before you do all of that, pull the lower cowl on the steering wheel. The ignition switch is located about even with the driver's right knee. Typically either the lock tabs are broken making the connection loose, or the entire switch crumbles into a gazillion pieces when you touch it. These are known issues and Ford has a recall on the ignition switch. Do not waste a day or more with Ford, the switch is less than $20 at a local parts store. It takes under 20 minutes to change. If the harness connector has to be changed, it is a bit more than $20 and it might have to be ordered. That will take a little longer because you have to splice wires, or unpin the contacts from the OEM connector and place them in the new one.
If the connector clips are broken, do not give into the urge to use zip ties to keep it fastened tightly. It is an OK temp fix, but the plastic is already brittle and zip tying it is a fire waiting to happen.
The next place to look is the Main Light Switch, especially on a GT. If the switch or connector show heat damage, those need to be replaced. You will also need to trace the wires out to the headlights to see if any melted together and are energizing the horn circuit. This is less likely than the ignition switch being the culprit, but still is a possibility.
I have the EVTM for 93, which is going to be almost the same as a 92 as far as lights and horn go. If you start chasing wires, or need to figure out why something is not working as you remove the alarm, let me know. If you use Facebook, I can send what you need via messenger.
Electrical and electronics are my expertise. I leave the greasy gears and engine internals to others.
Thanks for the help! I took the dash out and started chasing wires and I’m glad I did. Found a whole mess of problems behind there. However that wasn’t my problem. It looks like my problem was where the main harness connects to the headlight harness. Someone had messed with the connector and switched the brown wire with the dark blue. Which caused my horn to go off when I hit the switch. Now, I just have to figure out my wiper problem. I get 12 volts at power but when I turn on wipers I don’t get voltage to the others. I’m thinking it might be the interval govenor! If I could get that EVTM that would be great!
The wipers can be tricky. They should work on high when nothing else works. If not, you need to apply 12V to one of the terminals to make sure the motor works.
This is from an 88, but it is pretty much the same in all the fox bodies. The interval governor can have issues and I have repaired a few. If you pull yours and open it take some good high definition pics and I can try to see if anything looks obviously bad. There are capacitors on the board that can go bad. The other problem is one of the ground runs burning. As long as there is not too much damage to the IC's, the burnt ground runs can be repaired too. The interval governors can be purchased either new, used, or remanufactured. They can run between $30 and $130.
This is from an 88, but it is pretty much the same in all the fox bodies. The interval governor can have issues and I have repaired a few. If you pull yours and open it take some good high definition pics and I can try to see if anything looks obviously bad. There are capacitors on the board that can go bad. The other problem is one of the ground runs burning. As long as there is not too much damage to the IC's, the burnt ground runs can be repaired too. The interval governors can be purchased either new, used, or remanufactured. They can run between $30 and $130.
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