I was part of this thread with my 07 e250 van....

I now have an 05 Winnebago Aspect 26a on an E450 chassis. It has a tow package from the factory whether it be Ford or Winnebago Anyway, the RV has a 6 pole round receptacle. My trailers are 7 pole flat of course.

So i watched some etrailer videos and went to tractor supply and bought a 6 pole round to 7 pole flat adapter,


I already installed the tekonsha p3 brake controller. No issues there. So i connect the trailer, with the adapter to the RV and i have trailer lights but brake controller not working. In the etrailer video it said that in the 6 pole end of the adapter, the blue and black wire may need to be reversed for trailer brakes to work....I did that, and still no trailer brakes but i do have trailer lights still.

What next? Run a complete new 7 pole flat receptable from the RV rear bumper to the front or splice it in somewhere along the way to the cab? All the wiring is there, but the 6 pole receptacle is my problem. Thanks