Tucked in the door of my truck was a trailer wiring jumper harness. What is it used for? The truck has 4 pin and 7 pin trailer ports already wired.

I've read about issues people had with previous generation F-150s where the trailer battery relay and fuse weren't installed. That doesn't seem to be the case with my 2016. Though I don't see where the trailer battery line gets power. It isn't listed in my fuse diagram. Don't even have a slot #21 in the engine fuse box. Oddly, just a 21A and 21B.

In any case, this jumper has nothing to do with the trailer battery line. As far as I can tell. What is it?

http://jeffdeutsch.com/tmp/trailer_jumper.jpg


Jeff
2016 F-150 XL Extended Cab, 4x4

 

Aftermarket trailer brake controller harness. Hook your brake controller to the loose ends and plug the other end into the factory harness behind the small cubbie hole that is just to the left of the stereo.

 

Doh! So obvious now that you told me! Thanks!

 

Why not get a factory brake controller? That will integrate with the computer, I believe the dealer has to enable it.

 

The factory brake controller is beautiful. Tell it how much your trailer weighs, and it calculates the braking ratio between vehicle and trailer. LUXURIOUS. So dang nice.