Electrical Fire - Under Dash

[DirtDonk]

Well, we know a few things.
A severely melted wire like you’re describing is the result of a dead short circuit to ground. Or if it’s already a ground wire, then positive voltage was applied to it.
So if it’s a ground wire for the radio, and it touched the accessory stud on the ignition switch, then that is indeed your culprit.
Hopefully the wire was a smaller “sacrificial” gauge and it’s the only thing damaged.
Most of the other circuits attached to the Black with green wire on the back of the ignition switch are in the fuse panel.
At the very least then, if you have not already, inspect and/or test the accessory fuses.

If the ignition switch is not damaged, just turn it on. Sit there and look under the dash while you turn the key to ACC first, and see if anything is out of sorts.

 

[BruiserOutdoors]

From what I’m seeing in your video, the wiring that burned up seems to all be for the aftermarket stereo, and none of the factory wiring was damaged. Unhook all of the stereo wiring and get it out of the way so you can see the dash wiring better. Also, that wire with the fork terminal on it was most likely a ground wire. If it touched the post on the back of the switch, it would definitely look like it does now. I used to install stereo systems as a side gig back in the day, and a lot of aftermarket head units would have a terminal like that installed on the ground wire.

Weird thing is, the radio would still power up (but non-functional because no speakers). So if the ground was off, I wouldnt expect the display to show up?

 

[BruiserOutdoors]

Well, we know a few things.
A severely melted wire like you’re describing is the result of a dead short circuit to ground. Or if it’s already a ground wire, then positive voltage was applied to it.
So if it’s a ground wire for the radio, and it touched the accessory stud on the ignition switch, then that is indeed your culprit.
Hopefully the wire was a smaller “sacrificial” gauge and it’s the only thing damaged.
Most of the other circuits attached to the Black with green wire on the back of the ignition switch are in the fuse panel.
At the very least then, if you have not already, inspect and/or test the accessory fuses.

If the ignition switch is not damaged, just turn it on. Sit there and look under the dash while you turn the key to ACC first, and see if anything is out of sorts.

is there a way to "cap" off that stud terminal so wires don't hit it and short out?

 

[Oldtimer]

Looking at refelection in your photo, I hope the plate on the back of the switch is plastic (insulated) and not shiny aluminum?

You could insulate it with a Cable Cap Stud Insulator, but mine has been bare for 56 years and has not shorted out.

 

[DirtDonk]

Yes. I mentioned it earlier where you can put a short length of rubber hose over it. Easy Peezy.
You could probably even use a vacuum cap, but those aren’t known for living long lives after they’re exposed to air.

 

[BruiserOutdoors]

View attachment 929061

Looking at refelection in your photo, I hope the plate on the back of the switch is plastic (insulated) and not shiny aluminum?

You could insulate it with a Cable Cap Stud Insulator, but mine has been bare for 56 years and has not shorted out.

View attachment 929062

yes its plastic

 

[BruiserOutdoors]

Yes. I mentioned it earlier where you can put a short length of rubber hose over it. Easy Peezy.
You could probably even use a vacuum cap, but those aren’t known for living long lives after they’re exposed to air.

I missed post #10. A piece of heat shrink, closed shut on the end would be a clean solution. I did that on other exposed/unused wires

 

[rocknhorse76]

Weird thing is, the radio would still power up (but non-functional because no speakers). So if the ground was off, I wouldnt expect the display to show up?

The radio can also be grounded through the metal chassis touching the metal dash panel.

 

[BruiserOutdoors]

The radio can also be grounded through the metal chassis touching the metal dash panel.

I also thought that might be the case