Use a multi-meter and do some testing. See what the current draw, voltage and resistance is along with continuity from the fuse to the bulb. That is about all I can tell you. Maybe someone else will chime in and provide more for you.

 

This is for a 2001 47RE, but it should be very similar:


I'd set you meter to measure continuity, and have the alarm on. Unplug the fuse and bulbs. Plug the meter in where the fuse came out of on the "cold" side. Put the other end to ground. From their, wiggle the entire harness from the fuse box to the reverse switch. If it goes off, you have short to ground between the fuse box and B/U switch. Put the truck in reverse, engine off of course, and wiggle the wires between the B/U switch and the tail lights. You should be able to find out if you have a short to ground or not doing this.

Also, check for continuity between the B/U switch body, and the terminals in it.

 

speaking of witch where is the neutral saftey swith at I have a no lights on my truck and want to fix it Im tired off pulling out the flashlight to see behind me..

did not mean to steal your thread sorry!