85 Chevy, all electrical out, Help Please
 

So I have my truck for sale. It's an 85 Chevy and works pretty well. As we pull back into my driveway and go over a small bump, all of the lights go out.

Please give me some direction on where to start. It appears that all accessory things are out. All interior lights, headlights, radio, dash lights all out. I'm thinking that it is either some kind of short to the fuse panel or a ground issue. I have a haynes manual, but am not the best at reading a straight schematic.

Where are the standard main ground points/wires? Where should I look to start? Not excited about it, but if I have to rewire the whole truck I will. Also, please suggest the gauge of wire. It looks like most of it is 18 ga, but not sure.

I'm pretty handy in general but have typically stayed away from wiring systems in cars(although I've completely rewired more than one house).

Any help appreciated.

Does the truck still run? Cause that could eliminate some things from your search. If it still runs, then you have a different issue than a main ground or something like that.

Yes, the vehicle still drives great. I'm thinking it's the main power run to the fuse box or some kind of ground.