I have a 2019 f 350 and when pulling my camper, I got the trailer wiring fault, and my trailer brakes locked up . I switched over to my f250 work truck, and everything was fine, so it is on my truck end. I switched the 7 wire adapter on my truck with a brand new one and have checked all the fuses, and still having this issue. Do anyone have any ideas on a fix before I book it in with ford and spend a **** ton of money for maybe an easy fix ? Thank you

 

Welcome to the site...
Does it 'pulse' the brakes hard when you get the trailer warning?

My 17 did the above and it was an issue with one of my brake magnets.
Towed it with another truck and no issues. A repeat on my 17 again, and I changed out all the backing plates with loaded ones more because linings were pretty gone. Have towed thousands of miles with no more issues.
What I did do as a test was mount all the magnets to a plate and left them plugged in for hundreds of miles. Nothing.. Failure would occur with heat.

 

On these M/Y you can't use a plug in type trailer simulator, it would have to use a trailer isolation box if suspect of the trailer.
Does it lock at rolling speeds?
Have you tried towing anyone else's trailer?

 

haven’t tried towing anything else, this actually happened last summer, and I’ve just been using my work truck ever since for towing . But everytime I start my 19 since this happened, as soon as I move the truck, trailer wire fault pops up on my dash. I could also smell electrical the time it did lock my trailer up , so I have not tried towing anything else.