Transmission Problem?

I have a 93 Grand AM 3.1L with the 3t40 trany. The problem is that sometimes, more often that not lately, after I come to a stop the transmission hangs in first gear. At the same time the speedometer will stick on 0. Eventually, but seems to be getting worse, the speedometer will take off and the car will shift out of first gear at the same time. Runs smooth and changes 2nd to 3rd gears fine.

I have done a little research on the subject and had come to the conclusion that it was a speed sensor. So I took the car to a shop and they put it on the putter and said that it came back with codes indicating internal transmission problems? This shop does not do internal transmission work so I tend to believe him. I called a transmission shop and, no surprise here; he said I needed a total rebuild.

I have worked on and around cars most of my life and do have some mechanical experience years ago but am not too swift on the new generation cars. Just doesn’t make since that the speedometer works or doesn’t work in connection with the car shifting. The guy at the tranny shop said that the speedometer on this trany is cable driven and would have nothing to do with the shifting of the car. He said that I could possible have some broken parts inside causing the simultaneous problems.

Any thoughts or help would be greatly appreciated.

did the shop give you the codes, or tell you exactly what "internal transmission problems" it indicated? From what you indicate, it sounds like a bad VSS (veh speed sensor). The trans won't shift until the speedo moves, because the ecm isn't getting a signal from the vss that it needs to shift.

Haven’t gotten to the shop to get the car or codes yet but he said that he did have them written down for me. I am a Locomotive Engineer and I keep this car at the other end of my run so I will have transportation while I am laying over waiting on a train to bring back. It may be a few days before I can get there at a time when the garage is open to get it.

The VSS was my initial thought. I took it the shop to have it change because of the situation I explained above and also I don’t think most parts stores will take that part back if it’s not the problem. Then after talking to the Trans Guy I am totally confused.

Is the Transmission electronically controlled? He says its not but again it makes no sense that the Speedo and the shifting problem exist at the same time if it wasn’t.