4L60E Shifting Issues

[magnum440]

Hello, I'm new here. I have an '02 2wd Tahoe that when cold you have to shift it manually. If you try to start in OD position, it will just rev like in neutral. Most of the time after it warms up, you can start the engine and put it in OD position and it will go the way it's supposed to. Sometimes even warm you still have to shift manually. Once you have shifted it manually and come to a stop, it will take off like it's supposed to. Any ideas?

 

[magnum440]

Also, looking at the pan and drain plug, I don't think the fluid has ever been changed. I'm the second owner.

 

[badazzbulldog]

check engine light on? if so have the codes read for the trans and go from there

 

[magnum440]

No check engine light. Checked for stored codes, none there. I have been told everything from control box on outside of trans, ECM and hard seals inside trans.