I have a 73 F100. I have a Sony AM/FM with a CD deck.
The wire on the stereo that is supposed to be hot all the time on the stereo is wired in to the big yellow wire on my ignition swith, which is also hot all the time. The wire on the stereo that is supposed to be hot with the ignition on and the stereo ground wire are spliced in to the original AM radio plug which is a blue wire with a red stripe and a black wire with a green stripe. I've run my truck this way for about 6 months with no problems. Now all of a sudden I end up continuously blowing the fuse for my dash panel lights. I pulled out the guage cluster and didn't find any problems. I pulled out the stereo and found that the wire that is hot with the ignition switch on had a bare place in the insulation. I taped it up, and the guage lights started working with the stereo unplugged from the harnes. The minute I plugged the stereo back in, it blew the fuse again. The stereo still plays fine, but I can't keep a fuse in the fuse box for the dash panel lights as long as I have the stereo plugged in. Any one have any bright ideas?
Mike

 

are all the wires the same guage, try running new wire instead of using factory it could just be destroyed or something
Don

 

Don,
While I had it apart I added an ash tray light, glove box light, and cigarette lighter to the same circuit. Evidently, that was more pressure than it could bear. I made a new circuit that put the stereo by it self, and everything works great now.
Mike