I recently acquired a 2008 Ram 3500 quad cab cummins cab and chassis, and built and installed my own haybed for it. I wired up all the lights including dual trailer light receptacles just fine, with one exception..... I couldn't find ANY wire that was hot in reverse but not the rest off the time. I have checked every fuse in the truck. What color is the reverse light wire? And more importantly, what energizes the circuit? Is it a switch on the transmission?