" Tow/Haul doesn't lock out any specific gear " Wrong.My Owners Manual for my 19 Duramax /Allison specifically states that when in tow mode, with shift selector in L, not D, you will have access to the gear you select and all gears below that. So if you select 4th, then 5th and 6th are locked out. If you select 3rd, then 4th, 5th, and 6th are locked out and you only get 3rd, 2nd, and 1st. .It will not shift up into those 4th, 5th or 6th. I'd call that locked out.
Maybe it is in the transmission and not torque converter, as I am not a big gear head, but of you are pulling a pretty good load, have the transmission in Drive in hilly country or say from Kansas city to Denver where you are constantly climbing, you can sure fry the transmission before too long. Don' t know about present but previously Fords were notorious for that. You sure don't want to use Cruise Control either.( That is in the Manual too)
I drove almost 1500 miles this past hunting season with a heavy load. All hills/mountains were in tow mode,only flat Interstate was not. About 1/3 of that. I'm pretty sure I know how it works .
Last edited by saddlesore; 01/07/20.
