I have a 2500 Ram and not sure if it's the same OEM brake controller but guessing it is. Just picked up a new 5'er this week. On our older TT I had trouble with the Rams controller not locking up the brakes and it didn't matter whether it was set to heavy or light. And I also adjusted the TT brakes when these this problem occurred. The TT was 7300lb loaded. On the new 5'er (8500lbs)I noticed a big difference from heavy to light settings. With the heavy it really stops hard when coming to a stop. Even with the gain set at 3. I switched to light and set it to 5 and it smooth as butter. Bigger brakes on the 5'er. I would adjust your TT's brakes and if that doesn't help then it may just be that your hybrids brakes aren't strong enough to lock up or are worn too much. FWIW I couldn't lock up our TT's brakes either.
Also we towed the same 7300lb TT with a 2010 F150, OEM controller and could lock up the brakes on the TT with it. When we 1st hooked up the TT to the 12 Ram I had the same issues as you. Took it back to the dealer and the found the OEM controller was bad and replaced it. I was better but not near as good as it is now with the new 5'er. Not sure what to make of all that though. I do know that Ram has had TBC issues and not sure if they have been totally resolved. You may have a bad one from the get go. I know I did.
