6L80E problems

[1khp]

On my 2010 Sierra Denali 6.2 AWD, while cold it’s shift normally. After less thean 1/4mile driving the transmission seems to stop working and won’t pull in for work reverse until I cycle the key and then it revs real high to make it move and idles high at that point. Anyone have any pointers? Thanks in advance. 

[riverbanks]

Fluid change ever?sounds like a clogging filter

[It's Tim]

Fluid level / condition?

[swathdiver]

5 hours ago, 1khp said:

On my 2010 Sierra Denali 6.2 AWD, while cold it’s shift normally. After less thean 1/4mile driving the transmission seems to stop working and won’t pull in for work reverse until I cycle the key and then it revs real high to make it move and idles high at that point. Anyone have any pointers? Thanks in advance. 

Your shift solenoids are stuck and a Tech-2 can run a program in an attempt to clean them, get them unstuck.  The solenoids can be rebuilt without removing the transmission for about $90 off Amazon plus fluid and filter.  You can rebuild them on your kitchen table and then run the Service Fast Learn Adapts afterward and drive on.  

 

But I'm getting a little ahead of myself, you need a bi-directional scan tool to see what's going on inside, whether there are internal codes yet or not.  How old is the fluid?