Reel Deal,, What kind of truck are you pulling with... When pulling trailers in my old 2003 Silverado the running lights would never work if the truck light switch was in the auto position. I would always have to flip the light switch to the ON position. Just something you might try before you go chasing wires etc.... I bought new Silverado last year and have not had a trailer hooked to this truck to see how the lights work on it...