# Smoking wire from Coil?



## xconcepts (Jan 4, 2009)

So I was pulling my wiper motor and noticed I have a wire smoking from getting so hot. Its from the coil to a plug on the firewall. Does anyone have a wiring diagram or know what this is coming from? Its the yellow wire in the first pic and the upper right plug of the piece on the firewall, pic 2. Obviously a smoking wire is not a good thing.....


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## 05GTO (Oct 6, 2004)

That is the "resistor wire" bypass and it is hot when you start the car unless you have a bad switch and then it may be hot all of the time, under normal operating conditions, when the car is running you should have 8-10 volts on the + terminal of the coil. When starting the car you should have 13.8 volts.


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## xconcepts (Jan 4, 2009)

So if its suppose to be hot then why would it be smoking? Bad wire? Grounding possibly?


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## 05GTO (Oct 6, 2004)

That wire supplies full battery voltage to the coil only when you start the engine. If you ran full voltage to the coil while the car is running it would burn the contacts on the points. Remove the wire from the coil and check it for voltage while the engine is running, it should be 0v. Also while disconnected use the ohm meter and measure the resistance from the wire to negative. If that wire is shorted to ground it will short the voltage from the ballast wire to groung and may cause it to smoke. It may be a shorted wire to the chassis, a bad coil or a bad switch.


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## xconcepts (Jan 4, 2009)

05GTO said:


> That wire supplies full battery voltage to the coil only when you start the engine. If you ran full voltage to the coil while the car is running it would burn the contacts on the points. Remove the wire from the coil and check it for voltage while the engine is running, it should be 0v. Also while disconnected use the ohm meter and measure the resistance from the wire to negative. If that wire is shorted to ground it will short the voltage from the ballast wire to groung and may cause it to smoke. It may be a shorted wire to the chassis, a bad coil or a bad switch.


I am not running points anymore, went to a pertronix ignitor unit. This smoke is happening even when the motor is not running. So I need to check the coil or the wire for voltage after I remove it from the coil? 

And as far as testing resistance wire to negative, what would I use for the negative? I understand using the wire as the positive, where for the negative of the ohm meter?


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## 05GTO (Oct 6, 2004)

Things to check,

1) With the switch in the off position and the wires connected to the coil, set the volt meter to 20vdc range. Place the negative lead of the meter on the battery negative or a know chassis ground. Place the positive lead on the + terminal of the coil, you should not read voltage.

2) Disconnect both wires from the + on the coil, disconnect the positive battery terminal, set your meter to the 20k ohm setting. Place one lead of your meter on the battery negative or a know chassis ground, place the other lead on one of the wires that was attached to the + on the coil. Then test the other wire. You should not read any resistance or a short to ground on either wire.

Let me know what you find,


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## xconcepts (Jan 4, 2009)

05GTO said:


> Things to check,
> 
> 1) With the switch in the off position and the wires connected to the coil, set the volt meter to 20vdc range. Place the negative lead of the meter on the battery negative or a know chassis ground. Place the positive lead on the + terminal of the coil, you should not read voltage.
> 
> ...


05,

Ok so I tested both and have a zero reading, so no short or grounding issue. I did combine both positive wires going to the coil from that firewall plug. So only one positive on the coil positive. Could I be trying to push too much volts through that one wire? The wire is speaker wire that I thought was the same size as the original.


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## gjones (Oct 8, 2012)

*Speaker for the evening...*

Hopefully, you're not running speaker wire for electrical circuits, other than speaker circuits! (Unless you reeeaaallly want some burnt wires under the hood, or elsewhere!!!!!).


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## xconcepts (Jan 4, 2009)

gjones said:


> Hopefully, you're not running speaker wire for electrical circuits, other than speaker circuits! (Unless you reeeaaallly want some burnt wires under the hood, or elsewhere!!!!!).


Its not cheap wire, its OFC 12ga. I guess I'll pick up some regular wire from oreillys today


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