If you determine that the truck controller is OK-------
I had a problem with my 2011 8285WS brakes when I first got it. After all the trips to three dealers to fix the brakes, one dealer finally contacted ALKO about the brakes. The problem found was two magnets were bad right from the factory. After the repairs were made, the RV could not be moved when you applied max braking. Even with the emergency brake-a-way being activated, before the repairs, you could still move the RV with no problem.
Maybe you have a bad brake magnet!
Sid, Lois & HRH MISSY Terrible 2s SHIH TZU
2011 ROCKWOOD 8285 WS
2014 F-250 KING RANCH PS/SD/6R140/BFT
BOLIY PRO 3600SI GEN
DAYS CAMPED 2016 57 DAYS