# Wiring issue



## svk (Dec 21, 2019)

97’ Chevy 2500

All of a sudden this afternoon my running lights and dash lights turned on by themselves (the lights are turned off) accompanied by the smell of hot electrical. I couldn’t figure out the issue and it was getting dark so I unhooked the battery.

Where inhale do I start trying to track this down ?


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## steved (Dec 21, 2019)

Older truck, I'd start at the headlight switch. 

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## steved (Dec 21, 2019)

The older Dodge trucks run all the power through the headlight switch...and they fail quite often.

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## svk (Dec 21, 2019)

Great, thank you!!! I’ll start there.


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## sawnami (Dec 22, 2019)

Have you ever replaced any of the fuses with a slightly higher amp fuse? 

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## steved (Dec 22, 2019)

sawnami said:


> Have you ever replaced any of the fuses with a slightly higher amp fuse?
> 
> Sent from my SM-N950U using Tapatalk


That's a good point, the PO replaced all my fuses with 30 amp deals regardless of whether they were 30 amp or not...

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## svk (Dec 22, 2019)

I try to keep them to what is recommended or maybe 5 more. Really hoping it’s the switch.


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## sawnami (Dec 22, 2019)

That could be a problem.
We had a customer that was constantly blowing fuses when he towed his trailer so he put a 5 amp larger fuse in. It stopped blowing fuses but the higher current draw overloaded the the related wiring in the headlamp circuit and over a period of time overheated the wiring until the insulation fused together until it got to the wire core then the harness smoked. The wires to the switch are 18 ga. and the max amp rating is 7 amps so they are easily overloaded.

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## svk (Dec 22, 2019)

Other than the trailer lighting fuses I’ve never had to change one. 

The concerning thing is the lights turned on by themself.


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## steved (Dec 22, 2019)

You should be able to track down what was burning even unplugged...that burnt plastic odor lingers.

There should be a draw on the system if the lights stay on, could pull the fuses then reinsert them until you find the one that causes the lights to pop on...then trace it from there.

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## svk (Dec 22, 2019)

Beautiful! Appreciate the advice!


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## svk (Dec 22, 2019)

It is not the switch. I’ve narrowed it down to the 50 amp fuse under the hood. 

What next? Pull dash? I’m pretty sure the snell is coming from inside the cab.


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## farmer steve (Dec 22, 2019)

svk said:


> It is not the switch. I’ve narrowed it down to the 50 amp fuse under the hood.
> 
> What next? Pull dash? I’m pretty sure the snell is coming from inside the cab.


Tagging @MechanicMatt Steve. I think he works at a Chevy dealer . Might have some insight. Sorry can't help more. Only Chevy I had was a 55 panel truck and that only had about 6 wires in it.


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## Sleepy (Dec 22, 2019)

Wouldn't hurt to have a look around and behind the interior fuse panel. Lots of circuits there.


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## svk (Dec 22, 2019)

I’ve confirmed it’s under the drivers dash-somewhere. 

I laid underneath and had my son plug in the main fuse. I can smell the issue but I can’t see it yet. 

Pulling the instrument cluster momentarily so I can have a look from the top side.


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## JustJeff (Dec 22, 2019)

Christine was a Dodge....just sayin..
Be careful!






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## svk (Dec 22, 2019)

Still couldn’t figure it out. But I guess I should have done more pulling of fuses before. 

It’s something tied to the “courtesy lamp” 20 amp fuse. I’m not really even sure what courtesy lamps do as even with the fuse gone I have all functions of lights.


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## steved (Dec 22, 2019)

svk said:


> Still couldn’t figure it out. But I guess I should have done more pulling of fuses before.
> 
> It’s something tied to the “courtesy lamp” 20 amp fuse. I’m not really even sure what courtesy lamps do as even with the fuse gone I have all functions of lights.


Courtesy lights are the map lights and such that work with the door...

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## svk (Dec 22, 2019)

Well then they have been relieved of their duty!


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## motorhead99999 (Dec 22, 2019)

Is 97 borderline era when they started running ground to switches instead of power? Could be a wire rubbed through and sending ground to the lights. Check out side of switch for continuity with ground


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## sawnami (Dec 24, 2019)

svk said:


> Still couldn’t figure it out. But I guess I should have done more pulling of fuses before.
> 
> It’s something tied to the “courtesy lamp” 20 amp fuse. I’m not really even sure what courtesy lamps do as even with the fuse gone I have all functions of lights.


.






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## Lionsfan (Dec 27, 2019)

I had an 88' 2500 Chevy that the back side of the fuse box shorted out. I simply went to in-line fuse holders and by-passed the fuse box for the affected circuits.


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