Just hooked up a wire connector to work trailer lights to a small trailer, On an f-150 2003 model, I do not have power at the factory supplied pig tail, I checked fuses and they seem to be fine, I do have tail lights and brake lights and reverse lights as well as running lights on truck, but have no power at the trailer light pig tail wires from the truck, I followed the lead up to the factory plug where their trailer pig tail branches off, but do not have power on the yellow, brown , green!! Please help , Thanks

 

Check your ground. I had the same problem with yours. But I cleaned off my ground wires and made sure they were on exposed metal. And gracefully, that fixed the problem.

 

thanks for your info, factory ground was bad, but now i have running lights(both sides), and stop light and turn signal on right side only, best i can tell is i have no power from yellow wire at the truck lead, now what???