4L70E 1st Gear shifting issue

Hello,

I'm helping a buddy out with his 2007 Avalanche, 5.3L. Problem just started out of the blue. The truck will not shift out of 1st gear without lifting off the gas. Doesn't matter if you are WOT or just normal driving. The other gear changes are fine. There isn't a CEL. I have attached a log file and the current tune file. Any help would be appreciated.


Attachment 95174
Attachment 95177

You likely have an issue in the second gear servo, or a broken accumulator piston. Its commanding second gear, just doesnt shift, then goes straight to third when its commanded.