Electrical fire - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 9 (permalink) Old Dec 11th, 09, 05:10 PM Thread Starter
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francis
 
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Electrical fire

Hi I have a 68 RS Camaro and its just developed a problem with the electrics, on 2 occassions I have been driving the car one was at around 30 mph the second at 60 mph, the car just cut the engine for no apparent reason then there was smoke from under the hood and dash board.
The wire from the positive terminal on the battery to the junction box on the back of the radiator frame just melted and caught fire, the gauge cluster on the dash caught fire under the steel strap on the back of the gauges (I presume its an earth strap), I replaced the first time the junction box wire and cleaned up around the dash panel and the car started and went fine for about 2 weeks today the junction box wire again melted, replacing it the car is pretty well fine again and running, everything is working properly with exception to the gas gauge which is reading way under empty and also the 2 indicator lights on the dash stay on. the car has no extra electrics, its only running engine wiring, lights, horn dash lights, no radio, air condion or anything.
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post #2 of 9 (permalink) Old Dec 11th, 09, 05:54 PM
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David
 
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Re: electrical fire

Quote:
Originally Posted by twistercamaro View Post
Hi I have a 68 RS Camaro and its just developed a problem with the electrics, on 2 occassions I have been driving the car one was at around 30 mph the second at 60 mph, the car just cut the engine for no apparent reason then there was smoke from under the hood and dash board.
The wire from the positive terminal on the battery to the junction box on the back of the radiator frame just melted and caught fire, the gauge cluster on the dash caught fire under the steel strap on the back of the gauges (I presume its an earth strap), I replaced the first time the junction box wire and cleaned up around the dash panel and the car started and went fine for about 2 weeks today the junction box wire again melted, replacing it the car is pretty well fine again and running, everything is working properly with exception to the gas gauge which is reading way under empty and also the 2 indicator lights on the dash stay on. the car has no extra electrics, its only running engine wiring, lights, horn dash lights, no radio, air condion or anything.

I would start with a through examination of the wiring to see if there are any wires that have developed abrasions due to them rubbing on a exposed edges of the sheet metal i.e. radiator core support, or perhaps a wire has gotten pinched between something causing the short in the electrical system. I wouldn't drive it until this problem is resolved.

David F.

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post #3 of 9 (permalink) Old Dec 11th, 09, 08:37 PM
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Re: electrical fire

Definately a short circuit. Make sure none of the wires in your harness have melted through the insulation and shorted together. It's a tell-tale sign of improper fusing. The wire between the battery and the junction block should be a fusable link (at least the OEM was). Some aftermarket battery cables just use regular wire from the B(+) clamp to the junction block. If that is the case, then fusable links should have been installed between the junction block and the other branches of the system (horn relay etc.). Make sure none of the fuse-block fuses have been over-sized. Do you have an aftermarket ammeter with an internal shunt? If those wires find ground they'll short lots of current to ground - especially if they're not fused (with a fusable link).

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post #4 of 9 (permalink) Old Dec 11th, 09, 09:42 PM Thread Starter
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francis
 
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Re: electrical fire

Thanks for the help, I've checked most things and found if I take out the disconnect the light switch, everything returns to normal or run car without lights, if I disassemble the light switch and turn lights on manually through switch everything is ok, could it be a short thru the switch or especially the dimmer phase?
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post #5 of 9 (permalink) Old Dec 11th, 09, 09:59 PM
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Re: electrical fire

It may be...shorts happen. What concerns me is that it resulted in an electrical system meltdown instead of blowing a fuse, or at worst, burning a fusable link.

A good trick for isolating shorts is to disconnect your negative battery cable and then insert a test lamp between the negative battery post and the negative cable. Any current draw on your system will illuminate the light and the intensity will be proportional to the drain. A dead short will light it up bright. The test lamp not only gives you a visual indicator, but it also acts like a current regulator and won't allow more than about 1A to flow. It allows to you wiggle and isolate various parts of your electrical system until you find your short.

I'd keep the battery disconnected until you certain the fuses are properly rated and the fusable links are in tact. I'd hate to see you loose your car in a fire from a simple wiring or fusing mistake.

Dave
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post #6 of 9 (permalink) Old Dec 11th, 09, 11:08 PM Thread Starter
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francis
 
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Re: electrical fire

thanks for the info I will try the lamp trick, the car is only equipted with the fuses in the fuse box, theres no inline fuses but I will put one in the line to the junction box. i will see if I can get an electrical guy out on Monday my thought is that the dash light dimmer part of the switch may have caused it especially having lights on the first time melted the wire plus overheated the earth strap on top of gauge cluster, 2nd time no lights on and just melted wire.
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post #7 of 9 (permalink) Old Dec 12th, 09, 12:00 AM
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Re: electrical fire

I worked in an auto electric shop before leaving for a job as a fireman. The first thing to realize is that the engine did not stop for "no apparent reason" as you said. The fact that the positve cable melted at the battery means the short occurred before that circuit's fuse. I would check your wires around your headers or exhaust manifolds. Any melt to the exhaust? The fact that the engine stopped means it distrupted your ignition circuit or fuel circuit if you have an electronic pump. A short has definitely occurred. I definitely suspect engine compartment around exhaust first.

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post #8 of 9 (permalink) Old Dec 12th, 09, 12:35 AM Thread Starter
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francis
 
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Re: electrical fire

thanks checked pretty much with the lamp trick didn't flicker or glow at all with checking engine bay area and under dash, car is working fine without the headlamp switch connected, one thing though is the current wire to the mallory twin point was loose but since have tightened it up could that have been the culprit at all, what made me suspect the lamp switch is when you turned the brighten/dull part of the swith it did make the dash indicator left and right glow together and the fuel gauge went way down.
Everything is pretty basic on the car not much really to go wrong had the car for 28 years and its always been a turn key and go car. Its running a mechanical fuel pump and the wires running past the headers seems ok, I've routed them through some heater hose to protect them so shouldn't be a problem there.
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post #9 of 9 (permalink) Old Dec 15th, 09, 08:08 AM
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Re: Electrical fire

im betting your ground isnt connected to your lamp switch.
or its time for a new harness or else youll be chasing shorts for awhile.


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