4L65E - Slow to shift

[indulf]

I've done a ton of reading and research, but wanted to reach out here to see if I can get some more info.

04 Denali, AWD, 4L65E trans, 200k, well maintained.

The truck doesn't bang into R or D when shifted while sitting still.

The 1-2 shift is fine, but sometimes it holds in 2 without shifting to 3. There is no slipping, and the reluctance to shift is intermittent.

The issue is more likely to appear if I am getting on the gas to accelerate quickly, like if I'm on a highway on ramp.

The 3-4 shift has no issue.

The jury seems to be out regarding the fix of this issue. May be the first signs of something necessitating an R&R, may be a solenoid, and on and on.

Have any of y'all been there / done that? Any suggestions? I'm going to take it to a trusted mechanic next week for a look, but I want to be fully prepared.

 

[Rivieraracing]

Gonna ask the questions anyways, how old is the trans fluid (miles), does it smell and/or look burnt, and is it topped off? Ever drop the pan and change the filter?
How long ago did this issue develop?

 

[indulf]

fluid has probably 20k miles on it.
doesn't smell / look burnt. level is good.
unsure as to filter status.
it's been doing it since i got the truck, not sure when it developed.

taking it to the trans shop tomorrow for a look.

 

[#1taho]

I had an intermin issue like that last year on my 4l60. It was a sticky valve in the valve body. Just had that repaired and has been good. Wish I didn't find it tho. It's slowed me down from my 6.0 and 4l65 swap