4l80e OD shiffting

[joepres10]

1996 GMC K3500 4x4 7.4 &4l80e trans

 

wont go into OD. I can stop put it in 4 low pull forward till it shifts stop go back to 2 wheel then most times it will shift into OD like normal. But once I stop I then have to do this all over again. The truck came with a power chips tunner and code reader. I set everything back to factory. I have a reuilt 7.4 from S & J engines. The tranny is original as far as I know with about 140,000 miles on it. It isn't showing any codes.

Any help would be GREAT!!!!!

[ChumminsDQ]

Sounds to me like a solenoid issue in the valve body or possibly a pressure problem. Where the extra pressure of the 4Lo is helping the valve. But being it is 1 gear only, I would think sticking valve.

 

Not a difficult change or terribly expensive, just got to be meticulous in putting the check balls back correctly on the valve body and that they dont roll while you put it back in transmission.