I recently purchased a 2000 9-5 Aero with auto trans. I was told by the previous owner it would only go into gear when it wanted to. The last time he drove it he made it a block from home and it would not go forward. I got it trailered home and in garage. The tranny fluid was overfilled and was very brown but did not smell like trans fluid or burnt trans fluid. I started my troubleshooting. There was no DTC's. Gear selector at trans moves with shifter. When shifter is in reverse, the reverse lights do come on. Drained and refilled trans with proper fluid. After getting to level and letting run for 15 minutes fluid still cold to touch. Unhooked harness to TCM and started and it thru a code right away indicationg no communication to TCM, and still did not have any gears. (p1923 I think it was, looked it up at that time and it was for the TCM comm.) Cleared the code hooked TCM back up and no code would come up. Went through all gears giving time at each but there isn't any grab of any sort or change in idle. When I go from reverse to park it will idle real low and even stalled a few times. I am thinking internal mechanical problems such as blockage or pump or valve body. But before pulling the tranny thought I would throw this out there to see if I could get any suggestions as I do know electronics are a big part of trans these days. Also this might be insignificant but the winter mode button will light up on the cluster however the sport mode does not. i dont know if that would indicate anything or not. I have tried the gears in winter mode but still nothing. Any suggestions would be greatly appreciated.