Dash Light/Taillight Problem
 

This is a problem I'm having w/my 73 Cadillac. I figured that all the GM vehicles are wired the same way, so I hope you guys can help me. I keep blowing the fuze that controls the dash, tail and parking lights. I'll replace the fuze, start the car up, and all the lights will work fine. If I start to drive it though, at some point in my journey, the fuze will blow. Sometimes it happens pretty quickly w/in a couple of minutes, sometimes it takes longer, about 20 minutes or so. It's really unpredictable. Again, if car sits, fuze is good. The fuze only blows when the car is moving. The book calls for a 4 amp fuze, and I have used fuzes up to 8 Amps, and the result is the same, again with the same unpredictability of how long it lasts before the fuze blows. This is driving me crazy....help.

had the same problem with my friend's suburban. Finally tracked it down to one of the wires to the taillights having worn thru the insulation and rubbing.
Had a similar problem whenever I hooked up my trailer, it would blow the fuse every time I hit the brake pedal. The ground wire on the trailer had broken.
Check these things out and you'll be able to find out what the problem is from there.

That's what I was afraid of. Think it's called a floating or hidden short. All those wires running thru that car are inside of those protective casings. This is not going to be easy.

Check out the wires that run along the bottom of the vehicle to the tail-lights. I had this exact same prob w/my 68 beater when I first got it. I traced the wires from the tail-light sockets back & found that when someone put a new exhaust system on they torched the old off & burned through the wires in that area exposing them & the 1st good bump they would short out against the frame.