I just bought a new boat and the trailer has a 5pin connector to control the brakes. I bought a 7 way to 5 pin adapter to match my 2001 F150 to the boat's wiring harness. When I try to back the trailer up, the brakes lock down. I also tried it with my dad's truck (F150) and it did the same thing. For some reason, I don't think the truck is sending the reverse signal to the trailer. Can anyone help me with this?

 

I looked at some previous threads and found the answer to my problem. I had to add a fuse to the box under the hood. The fuse was in a bag in my glove box and came with the truck. I'm not real sure why ford doesn't put them in the fuse box to begin with. Thanks to those who looked at my problem!