I recently had the headlight switch break apart in my 01. 5 2500, causing a short inside of it... it blew out the parking lights fuse in the power distribution box in the engine compartment, which I replaced. However, I still had no radio, dome/map lights, cargo lights, nor power mirrors. I checked EVERYTHING with my multimeter, traced wires all the way back to the power distribution box, but nothing.
I finally read through some TSBs and found out about the I. O. D. (Ignition Off Draw) fuse, the ONLY one I didn't check due to its PITA holder. Sure enough, it was blown due to the short inside the headlight switch... as soon as I swapped it out for a good fuse, everything came back on. Problem solved!