I bought this truck w/71,000 miles and had nit-pikking problems from day one, the latest is the parking lites don't work. Have had ongoing problems w/ trailer wiring that I can't seem to get right All the time, could the parking lites on the truck be a side effect of that? All the fuses under the dash check o.k. Is there another fuse box? Also seems since this happened the factory fog lites stopped working, thanks

 

My 03 F-150 has a fuse box under the hood also.
But when it comes to electrical problems,I'm kinda lost...lol

 

Moved to correct forum.

 

There is another fuse box under the hood, behind the left battery, and next to the power steering. you could have corrosion or chaffed wires somewhere on the truck, that could be causing your problems, the tow wiring, fog lights, or parking lights have to connection