Hi all,

I'm new to my 2003 GMC Yukon XL 2500 and I'm not fully sure if the tranny works as it should. On flat road, I need to exceed approximately 55 Mph before it decides to shift to 4th gear. I have a 496 (8.1Litre), 4L85E and 3:73 diff. I have changed tranny oil and filter, but that didn't change anything.

Is this what I should expect? Or should the tranny be tuned and is it only possible to tune the tranny with a Tech2?

Sven-Erik

 

Yes... I believe this is normal.

The 4L60 and 4L80e transmissions at least were actually 3spds and the fourth gear was an overdrive.

 

Thanks for that, really hope youre right.