66 GTO lsx - Wire in Bulk head getting hot/smoking when lights turned on
 

Hey guys,

My dad and I have pretty much finished up the ls swap in our 66 GTO (build thread to come). The car runs and drives and all that but we are having an issue when we turn on the lights. The wire in the bulk head that was supplying all of the accessories power inside of the vehicle is getting hot and smoking when the lights are turned on. From the old service manual i have it looks like that wire originally went to the coil, but we have coil packs now so i just had it wired directly to 12v. Currently it is unplugged, but now we have no power on accessories.

Is there another wire that could get power to accessories or should this not be going to 12v? Something maybe not grounded properly?

Im at a total loss and any help is appreciated. getting Married this Saturday and this is our getaway car.

Thanks!

The wire that originally went to the coil should be a 12V source for the coil with the ignition turned on. If you wired it directly to 12v battery and now have no accessories it sounds like you are back feeding all of your accessories through the ignition switch with that wire. There should be another red wire in the harness that goes direct to 12 volt battery and provides power to the accessories and the ignition switch. Headlights are typically wired to 12V battery so they can turn on with the ignition switch off. Some basic 12V troubleshooting needs to be done.

Well with that wire it was giving power to the acc. circuit, but it is possible that its back feeding, So with that wire plugged in we do have power on Acc. with it not on 12v, we do not have Acc. power. but with it on, and then turning on the lights, it gets super hot. So I will check and see if there is another wire on the bulkhead that provides power to the ignition switch. Any chance anyone has a color diagram from a 66 GM A body. I've had no luck online

Sounds like you are messing with the original resistance wire that went to the coil. It looks like regular wire but it is actually a special wire with certain resistance on it to feed the original coil. And yes, they can got hot, smoke, and melt other wires around it.

A little more info would help. What color is the wire? Did you take the end that was at the coil under the hood and give it 12v? Then you would be back feeding that circuit. That circuit should already have power fed to it from the ignition. Is your ignition switch and rest of the under dash/bulkhead wiring all factory stuff or has it been changed/altered?