Almost caught on fire!

Well, wednesday i hooked up my EBPV brake to the throttle. I had the main dash panel off along with the radio. I drove it yesterday and the radio didn't work, i thought that maybe i didn't plug the wires all the way in. Turned out to be the fuse in the panel. I changed the fuse with the correct (5amp), then drove to town. When i started my truck to come back home, smoke started rolling from the dashboard. I took the panel off and one of the wires had the insulation melted off of it. I have no idea what could have caused that, the wires i was messing with wednesday have nothing to do with the wire that melted. It was a black/pink wire. Im friends with a guy at the local dealer, he let me borrow a book that has the entire wiring system of these trucks. The wire goes to the radio, and to the headlight switch. Im guessing its the illumination, but i haven't looked into it that much yet.

DO NOT USE HARBOR FREIGHT FUSES!!!!!!!!! that is what i replaced it with, and the wire melted and the fuse was still intact.