Fuse Box Wires Melting

Whenever 12 volts is applied (battery is connected), the wires begin to overheat and emit smoke. Key is OFF. It appears to be both the large black and the large white (look to be main power) going into the box. Any theories?

As you can see in the pic below, a previous owner has done a bit of fiddling with this car.

Umm is the main black wire attached to the same terminal as the white wire (power wire) if so that's wrong and a good way to start a fire

Well, you can see the pic yourself. The biggest white wire is going alone to one side. There's another slightly smaller white wire that connects with the ground at the same terminal. Should that wire go somewhere else, maybe? Does anyone have a pic of a stock fuse box connection?

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actually I stand corrected. I have a red wire going to that terminal on my car but it appears some harnesses did have a black wire. See the images in this topic

viewtopic.php?t=26689

Either way you obviously it looks as though you have a major short circuit or the hacking of those wires have left them unable to carry the amperage load required of them. My bet is on a short since it happens without the car on. You can check this with a multimeter by checking to see the if the resistance between that terminal (black and white wires gong to it) and ground is 0. It should be infinite when the battery is not connected.

Good call. I'm getting close to 0 resistance between that terminal and the ground behind the headlight with the negative battery cable disconnected. Any tips for troubleshooting this? Never really had to trace down a short before.

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