2013 f150 eco. I first encountered my brakes surging like the ABS was engaging when I first picked up a new travel trailer. When I tried to set the gain my trailer brakes engaged on and off while holding the controller paddles. The magnitude would differ at difremt settings but still on/off untill I came to a copleat stop.
it does this every time I stop.
Trailer dealer took a look and said that drums on trailer might be slightly out of roung, give it 200 miles...
well after 200 miles still have the problem. returned to trailer dealer to complain, they said they checked it out and all ok, must be factory brake controller.
I just returned from Ford Dealer and my controller checked out just fine!!
My question is who do I press for answers Truck dealer of Trailer dealer??

 

Given the general quality of new travel trailers, personally, I'd pull the wheels, take a peek at brakes, adjust old school style, and manually repack the wheel bearings. I'm on a few RV Forums and the trailer industry is scary with the quality. Maybe ask RV dealer if you can connect and tow another trailer for comparison?