TH400 Troubleshooting
 

I have not driven my car for a few months. When I got in last weekend the transmission would not shift into second or third. Park, reverse, etc. were ok.
I checked the fluid. It was a little low so I topped it off. The vacuum seemed ok, from the throttle body. I have not yet checked the electric kick down.

I changed the fluid and now it shifts into second, at about 3500 rpm. Any ideas?