Sorry guys this may be kind of a dumb question. I am new to the duramax, I just switched over i was always a 12-v cummins 5 speed guy. Anyway my question is; Last weekened I was pulling my horse trailer with a couple horses home and I had to go down a few big hill. Now my understanding and from what I have seen from work pickup (an 08 3500hd duramax with service bed) is that when you put it in tow haul it will downshift as you are trying to slow down. I have always known this that was why I really like the chevy automatic, but i was under the impression that when you turned tow haul off it would not longer downshift automatically? My 08 work truck as long as tow haul was off it would not downshift so i just left the button on at all times because other wise it was slow to stop because it was using all brake with a load. Trips the scales at about 16,000 empty with just my tools. So is the 5spd that is in my pickup suposed to downshift with tow haul off? My problem was i would want to just touch the brake every know and then and stay about 70 but every time i would touch the brake it would kick down and i would be at 3k rpm and at 60 miles an hour. It does downshift more agressively in tow mode.