I've got a 92 F250 (351w), my tail lights and license plate lights stopped working at the same time (headlights, reverse lights, brake lights, and turn signals still working). I checked the fuses and they all look good. I'm thinking the wires may have disconnected. It looks like the previous owner did some wiring work and left some wires disconnected on purpose which has made it difficult to trace the wires to see what goes where. Does anyone know where I could find a wiring diagram that may help me out? I tried googling and came up empty handed.

 

Here ya go, diagrams make the job easier.

http://www.justanswer.com/ford/2rse5...ng-lights.html

 

If you go to your local auto parts store they usually carry the haynes manuals for about $25.

Other than that crawl under it with a DVM and start checking for bad grounds and or breaks in the wiring.