Ours is a 2011 with the 425hp cummins, and the brake is named ENGINE brake
some have exhaust brakes, some have engine brakes...
not sure I'm understanding what the issue is...
are you worried you have a tranny issue or ....?
are you turning the brake on and off all the time ?
some never use it, some use it sometimes, and others leave it on always...
I'm in the last camp and so as long as I am picking up speed or steady state on cruise, the brake is never activated and all works as it should...
when decelerating, the tranny downshifts to slow us down much faster...
but I can always just give it a little throttle to override it to keep up speed.
I rarely turn the engine brake switch off, but iirc, when I do, as soon as I accelrate, all goes back to normal - maybe yours completes the cycle while nothings changed ????