2500hd Harsh Shift

[andrew-mayer]

i have a 03 gm 2500hd wich sometimes shifts hard only on the up shift when warm the only codes i ever had was a air intake code anyone ever have this problem?

[2000DV4.8]

Which shift? (1-2, 2-3, etc...)

 

And try searching, it may have been covered before.

[alaska511]

If you have the Allison, go to your nearest Allison dealer and have do a Fast Adapt with thier DOC software...if it is not the Ally, disregard