[2sb]

If you want to tinker with your PT, I'd suggest getting a shop manual specific to it. Disc version is the cheapest (Ebay). Then you can trace out your wiring. For example: Your radio has a hot feed from BATT (clock), a hot feed from IGN (radio), and a hot feed from LIGHTS as a minumin. If they both go at the same time, I'd look for an intermittent ground. When checking connections, take them apart and put together a few times in case of corrosion. In the under hood Power Distribution Center, Fuse #14 is for horn relay and fuse #18 is for radio. These are powered by circuit BATT AO. This is from an '02 book. Happy Hunting!