Hi all, its been a while since I've been on here, really loving the 2011 F-150 with the 5.0, its got 105K miles on it now and still drives like new! We recently purchased a newer horse trailer, with electric brakes and the 7 pin connector and battery backup. The brakes work and normal lights work, however the interior lights and fans do not work. I have installed the relay and fuse but still nothing is working. I had a friend with the same truck hook up to our trailer and everything worked, only difference is their truck is a 2014 and they had the dealership install the relays/fuses. What could be causing the problem here? I also tow a bass boat every weekend and the trailer lights work fine on that one.

Any info is appreciated as this is becoming quite frustrating.

Thanks again,
DTS

 

It sounds to me like your truck's trailer battery charging circuit is not functioning. In my 2014, this circuit is powered by a fuse AND a relay in the fuse box at the front of the engine compartment. This circuit did not have the fuse and relay installed when I bought the truck - I had to do it. Your owner's manual shows you where these two items fit, and you can buy the fuse and relay at an auto parts store (if they're not sitting in your glove compartment).

I don't think your horse trailer has a trailer battery that powers the interior features, so they have to get their power from your truck through the battery charging circuit.

- Jack