[01AleroGL34SS]

I don't know if this will be of any help, but I'll give it a shot.

This is where my trouble begans, last week I discovered my battery was going bad. When I got to the repair shop to have my battery replaced, my transmission was fine, but after the battery was replaced, the transmission would slip between 1st and 2nd gear. If I shifted in manually, it was fine but if I let it shift itself it was slipping pretty bad, and even the shift between 2nd and 3rd was weak. I immediately called my dealer, explained to them what happened, and got the car over to them. After driving it, they told me the battery had nothing to do with my problem, and that my pressure solenoid was bad and I needed to get the valve bodies cleaned.

Not wanting to spend $700-$800 bucks, I called a local transmission shop. Turns out, when they replaced the battery, somehow the computer lost its memory. The computer didn't know when to shift the car! The mechanic plugged the car into his computer, and drove it around for like 25 minutes. He said to keep driving the car and the transmission would eventually go back to normal. Sure enough, that solved the problem.

I didn't know the Alero had a driver adapting transmission, but that was the problem. When they replaced your transmission, did they disconnect the battery? Any chance you could be experiencing the same kind of problem?

Almost forgot, my Alero has the 3.4 V-6