how many and where are the fuse box's in the truck?

Trailer light fuses are in the underhood box, but the light control module is under side of the truck, under side of tail gate area, and sometimes it fails.

When you open your drivers door look on the butt end of the dash for a triangular panel that snaps on. Pull it off from the bottom and it exposed the fuses. There are also extra fused on the back of the panel and a devise to pull the fuses.