Trail Rider

I recently bought a 2015 F150 XL Sport with towing package. Of the 1500 miles I have put on the truck, 800 miles have been towing. Last night I was towing my horse trailer (horse and trailer combined totaled less than 4000 lbs) down a large hill. As I tapped the brakes the entire trailer locked up and Trailer Wiring Fault displayed on the dash. Long story short, we figured out that it is the truck with the issue. We hooked our Dodge 3500 dulley up to finish the job (smh). Both the horse and I are shaken up over the experience but ok. I'm taking it back to the dealership tomorrow to get looked at, but I have read on this forum that it could possibly be a grounding issue in the wiring. Anyone else have similar problems and if so, has it continued after repairs? I'm sorta scared to pull again. Any thoughts or suggestions? Up to that moment I have loved towing with this truck! It's the little badass that could! Taking the WV mountains without a backward glance!

BlackKnight81

check out the thread form ddlaz 7/26/15 "Trailer Brake Malfunction"
it might be tied in to what your problem is too !!