Wiring issue

[svk]

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 ?

 

[steved]

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

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[steved]

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

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[svk]

Great, thank you!!! I’ll start there.

 

[sawnami]

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

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[steved]

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

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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]

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

 

[sawnami]

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]

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

The concerning thing is the lights turned on by themself.

 

[steved]

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]

Beautiful! Appreciate the advice!

 

[svk]

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.

 

[farmer steve]

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.

 

[Sleepy]

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

 

[svk]

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.

 

[JustJeff]

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

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[svk]

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.

 

[steved]

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]

Well then they have been relieved of their duty!

 

[motorhead99999]

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