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Tire Smoker
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Hi, I have a 87 GT convertible i'm putting together and i have a strange electrical problem. Hopefully somebody has ran into this before and has the answer because i'm kinda ripping my hair out at this point. OK to start it is the green wire with the yellow stripe that is in fuse circuit #8. It started out with the #8 fuse blowing all the time so i tried bigger fuses until i found one that would work. Ths circuit is the one that powers the Dimmer Switch, Radio, Glove box light, power mirror switch, courtesy lights, trunk light and so on. When i finally got a fuse to work i noticed that the courtesy lights would stay on no matter what, so i started looking at that. I pulled the dimmer switch, everything looked fine. The trunk light is not connected. I looked at the radio, fine. I started unplugging everything on that circuit and to see if it would stop popping the fuse, no luck. It sat there for hours with the radio on and was fine. I met a kid that had a fox (came to a party at my house) he wanted to see my car. I was showing it to him and he wanted to hear the system so i hooked up the jumper box and bam! Smoke started pouring out from under the dash on the passengers side. I unplugged it quickly. The next day i started to investigate it figuring the smoke was the problem for sure. It turns out, the green wire with the yellow stripe was fried all around the glove box area. I figured i'd be able to find it easily now because whatever caused it had to be the hottest spot so the wire would be most burned there. Still Nothing besides a fried wire. It is all burned around the glovebox area down to where the plug is at the kick panel. The whole rest of the circuit that runs down the left side of the car is fine including the dimmer switch. Any input would be great! Thanks, Brian. I also have the headlight harness off the car because the rest of the nose is off, IDK if thats any help.
 

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Sorry im not any real help, but i would like to add that you should never put a bigger fuse in, those wire/circuits are rated. Bigger fuses will burn up your wires but it looks like you know that now.
 

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Tire Smoker
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Discussion Starter #3
Thats one of the reasons i put the bigger fuse in. I had gone through everything and couldn't find the problem. I figured while the car is still apart i could get whatever the problem is to show it's self and i could replace whatever it happens to be. After i put the big fuse in it was fine for hours. It was the next day that i hooked battery power to it and it started smoking. Nothing was different than the night before.
 

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I went to go look for my wiring diagrams, but I couldn't find them at the present time. That leads me to believe that I left them in the house and my wife must have found a more appropriate place for them, unbenounced to me. If I can't find them soon, I'll reprint them at my buddies shop, but don't know when I'll be there next. In the meantime, don't EVER put larger fuses in to try and force something to blow harder/burn up. That's just stupid man. You're lucky your car didn't catch fire. Hopefully it's a lesson learned. You can easily do testing without a fuse at all using an ohm meter. I'm an electrician by trade, and although it's not 12volt that I play with every day, you wouldn't believe the **** I've seen and the fires that have started.
 

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Ive seen entire wiring harnesses go up in flames because someone used the wrong fuse. Ive even seen an entire fuse box go up in smoke. It isnt pretty.

The fuse keeps blowing because there is a short (the fuse did its job). You need to find out what is causing it. I dont trust burnt wiring. Any wiring that is burned, replace it. A crimp will work but solder and heatshrink is best. It is possible you burned off some of the insulation so check as much wiring as you can.

All i have on hand is a very small print wiring diagram out of my Haynes manual. As you already know, the light green/yellow wire from fuse #8 runs to the radio, the glove box light, both courtesy lights, trunk light, and the dimmer. Both sunvisor lamps, the swivel light above the rear view, and fuel door release also share that circuit.
 

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Is the trunk light not connected or not working? If it was me, now knowing everything that is on that circuit, I would investigate each lead for proper function. Seems that if the trunk light doesn't work, maybe that's where the wire is shorting to ground?
 

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I would trace the wire that runs to the courtesy lights and look for a bare wire and a possible short to ground like dbshea said.
 

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you need to check out each individual component on the given circuit then unplug each one,put a smaller then recomended fuse in then start hooking then components back up one at a time turning the ign off of coarse inbetween connections,one of the components could be shorted and this is one way to figure out which one
 

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Discussion Starter #9
Today i got a few minutes to screw around with it. The trunk light has always been unplugged. There are no burned wires past the plug that powers the switch in the door jam Everything on the drivers side is good so i put battery power to it, tooka a 7.5A fuse and touched it to the terminals in the fuse box it started making a sizzling sound instantly and the sound was coming from behind the radio but up further somewhere in the dash. I have to wait till my friend comes over to have him touch the terminals with the fuse while i put my head up under the dash and locate it. The car has an Alpine head unit that works fine and none of the wires are burned near that. I also tried it with the radio unplugged, no difference. It sounds like it's coming from up behind the heater vents in the center of the dash. I have a factory Ford electrical troubleshooting book for a 1990 and if its identical there is nothing up there that should be powered by this circuit. I'm starting to wonder if a mouse got in there and chewed some wires or something. I had trouble with those little bastards before with my RX-7. I'll keep you posted!
 

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The dash frame is flipped down in this pic, but you can see how there is wires going across the top (looks bottom in the pic) of the dash frame. They are all grouped together and they were taped originally before I was eliminating unused wiring. So as you can see, DO NOT keep taunting this circuit by applying power to it. If you have wiring burning up, you will fry it to other wires. I will cease to help if you continue, so don't be stupid about this man. As you can see, my car is in the position that I can help you. Take your dash apart and check things. Stop applying power to SEE what might happen. :facepalm: IF you disregard my warning, I really hope you burn your car down, cuz apparently you are hard headed and that's the only thing that will make you open your eyes.

 

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The dash frame is flipped down in this pic, but you can see how there is wires going across the top (looks bottom in the pic) of the dash frame. They are all grouped together and they were taped originally before I was eliminating unused wiring. So as you can see, DO NOT keep taunting this circuit by applying power to it. If you have wiring burning up, you will fry it to other wires. I will cease to help if you continue, so don't be stupid about this man. As you can see, my car is in the position that I can help you. Take your dash apart and check things. Stop applying power to SEE what might happen. :facepalm: IF you disregard my warning, I really hope you burn your car down, cuz apparently you are hard headed and that's the only thing that will make you open your eyes.

sweet pic and very well said!!!!!!!!!!
 

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Now you have sizzling? Not good. Not good at all. Pulling the dash is the only way to handle this. You had smoke on the passenger side (that was the insulation burning), and now you can hear a sizzle behind the radio A/C controls (probably metal to metal sparking). You have a major electrical problem. Stop applying power to the wiring or you run a high risk of buring the entire wiring harness behind the dash and anything sharing the circuit in question. This includes the fuse box.

I would not even drive the car until you fix this. The wiring is bundled as FastStang has shown and the only to get to it is to pull the dash. If one wire has burned the others are probably not far behind. You dont want bare wires touching the metal dash frame or another bare wire or you will more than likely be calling the fire department and that is no joke. I could go on but i think (i hope) you get the idea.

Pull the battery before you do anything.
 
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