Allison TCM "learning"

[Dusty Trails]

I went to 265's on my 2500HD and was wondering if I need to disconnect the batteries to clear the TCM memory so that it will change the shift patterns. Or does it continually change depending on load and/or driving style over a given distance? Thanks for any feedback.

[DmaxMaverick]

It will learn continually. Changing to 265's isn't that much of a difference, anyway. At any rate, you probably won't notice any difference. As far as the truck is concerned, it's no different than a couple extra bags of cement in the bed. I can't imaging needing to reset the 'puter with every trip to Home Depot. I haven't seen any consistent success to suggest disconnecting the batteries will reset it.

[EdHale]

How fast does the "learning" take place? I towed a 9,000 lb boat this past week about 500 miles and did use tow-haul mode. Frankly I didn't notice any difference in shifting immediately after starting with the boat or after dropping it off and heading home another 60 miles without it. Maybe I'm not too observant. Ed

[mark45678]

after a hard /heavy tow my truck is like a rocket for about the first 25 miles if you hammer it empty. after that its back to normal , almost like the TQ managment in the computer sences it cant get rolling with the same APP as normal and hits the fuel harder in the low gears loaded.

small tire size change like your stating you will not notice any change. I dont think powering down the TCM reset things like the old stuff built back in the dark ages. I did the tire up size thing on stock wheels , next tire change I will be going back to stock 245's the stock 6.5" wheels dont like wider tires. if your run over 50 psi of air the tires start to crown and handle like chit empty. ex: long tow with the camper and droping the trailer at the park and leaving the air up and running around all week with extra air then loading up at the end of vacation and heading home. all week the truck felt like the roads had huge valleys and the truck would just wonder and not track strait and true. put the weight back on it and its fine, same roads ? I run 265/75/16 LRE bridgestone REVO tires, stock I had the bridgestone sw773 AT tires.

[Dusty Trails]

I thought the transmission might be adaptive, but I wasn't sure. I will leave it alone. Thanks for the replies, guys!:)

[Kennedy]

Removing battery power does NOTHING to any of the controllers as far as learn or memory loss.

The Allison is in a constant state of adapt. It starts out Fast and then switches to slow. In order to get it to Fast you need to command it via scan tool. Fast learn is really only necessary when large increases of power or modifications to the transmission's Hardware have been made, or if a problematic shift occurs.