i have a 2500 05 cummins i changed some fuses that where bad and i dont know how long the light was out cause i dont know how long the fuses where blown any how i changed the bulb not it and checked the wire not getting power to the board only on the brake wire the middle brake light is fine and all my fuses are good checked them again and i followed the wire no power up to the diesel tank. The light works when the tail light is on and the truck reads lamp out when i push the brake??? thanks Dwain

 

2004.5 and 2005 trucks are the same harness... Check up beside the trans for broke wires more then likely you will need to inspect the hole loom. You might end up removing the hole loom from the IPM (fuse box on left inner fender). Or your just missing the brake light fuse... Also IDK if this works take a test light put it on the Brake light fuse see if their is power there. if not apply brake pedal if power is their then your good to the fuse box. I will grab a print out of the tail light harness so you can see what your up against...