Its a 99 Jimmy 4x4. I don't really understand much about how the lock up feature or how it works on these newer transmissions. Are they true 4 speeds or 3 speeds with converter lock up?
The problem or symptom:
When I take off from a stop at low load up to about 10 mphin drive or reverse it feels like I have big paddle tires on it or like on the shoulder of the interstate there are intermitten rumble strips, it feels like Im slowly rolling over those..Its not a noise but it can be felt.
Then when at a stop in Drive it chugs a little like the converter maybe going in and out of lock up. I can see it on the tach.
I bought it a couple months ago from a used car lot. They acknowledged this andput in writing that if something goes wrong within 90 daysdue to thisthing they would fix it for free! I have one month to go.
I have inspected the front susp. and everything is good and tight.
Thanks for reading.
Angelo, Joliet, IL.

 

you have a 4L60E automatic transmission. It is a 4 speed, lock up happens in 3rd and 4th gears.

Take it too a tranny shop for a diagnosis. Get the diagosis in writing and take it back to the place you bought it for repair work. Don't use the estimate as a shove in thier face, just say it was giving you toruble and wanted to ahve it checked out. Here is what they found, I hope it helps you in fixing it. Of coarse once they open the tranny up it could need a rebuild. fortunately for you you ahve a written estimate stating their is a problem from a 3rd party in case this does end up in legal action.