Had a similar problem with my Springdale several years ago. I even had it to a repair shop 3 times to fix the problem. First we thought it was the 7 pin on the truck. Changed that out. Worked OK for a short while and then brakes started failing again.
Next, changed out the pig tail on the trailer. This worked again for a short while and then brakes started failing again, controler whacking out, everything weird.
Finally, on the 3rd attempt, found out the wires going to the trailer brakes were rubbing and had a bare spot on them (both sides), and when everything was just right, the would short out, touch the rubbed spot against the trailer metal. Dealer repair shop fixed the wires, gave them a bit more length, and I never had problems again.
Check the camper, around the brakes, for wires that might have rubbed bare. Just guessing, but a close inspection will not cost anything.
Good luck!