Overdrive

[jbry31]

Hi, Recently I started experiencing problems with my transmission. My overdrive works sometimes and other times does not work. Was sketchy about changing fluid and filter so I talked to a friend that was a GM Transmission Tech for years. He looked, smelled of, and felt the fluid on the stick and said I could change the fluid and filter to start off. Tahoe has 198000 miles. I changed the fluid, filter, and of course the gasket. Added roughly 4.5 QTS to get it back to the operating level.

I am still having the same problem. May be just something I have not payed much attention to but seems like now it is also shifting into overdrive a little early. around 30 t0 35 MPH...

Any advice, suggestions, comments, similar problems?

(all other gears and reverse work great, nice solid smooth shifting, just OD giving me issues so far.)

 

[Jerky Arm Ape]

I read your post when you first published it.
Since then I have been paying attention to what my truck does.

Steady slow driving on mostly flat surfaces, I have gotten it to shift into overdrive at 40 mph.

Same driving uphill, it doesn't shift into overdrive.


Accelerating variously (redlight to redlight/ in town style driving) it doesn't shift into overdrive.

 

[jbry31]

Anyone ever heard of a vacumm problem causing a Tahoe not to shift into overdrive correctly? Was having a P1441 code. PSV solenoid was bad. I installed a new one and now my Tahoe is shifting flawlessly....

 

[livingez_123]

the 3-4 clutch pack is a high failure item.

 

[Nickn]

In your "service engine soon" light on? Were the valves in the valve body checked for movement when the pan was off? Any black clutch material on the bottom of the pan?

Hi, Recently I started experiencing problems with my transmission. My overdrive works sometimes and other times does not work. Was sketchy about changing fluid and filter so I talked to a friend that was a GM Transmission Tech for years. He looked, smelled of, and felt the fluid on the stick and said I could change the fluid and filter to start off. Tahoe has 198000 miles. I changed the fluid, filter, and of course the gasket. Added roughly 4.5 QTS to get it back to the operating level.

I am still having the same problem. May be just something I have not payed much attention to but seems like now it is also shifting into overdrive a little early. around 30 t0 35 MPH...

Any advice, suggestions, comments, similar problems?

(all other gears and reverse work great, nice solid smooth shifting, just OD giving me issues so far.)

 

[jbry31]

Well scratch what I said about the overdrive working well. It is not shifting into overdrive constantly like it should. Sometimes it does sometimes it doesn't. Seems like in the mornings it doesnt shift into overdrive but when I leave work in the afternoon it does. Really odd.

---------- Post added at 08:10 AM ---------- Previous post was at 08:09 AM ----------

I did not check the valve bodies.