I am the original owner of a 19842M4, manual transmission. Years ago I decided it would be a good idea to check my transmission fluid level. In the process of removing the speed sensor from the transmission I must have dislodged that purple sensor gear because when i put it back in place my speedometer stopped working. Also, my odometer stopped recording mileage. Eventually I was able to acquire a new purple speedo gear (from the Fiero store). After installing it my speedometer worked, the "shift engine" light worked and I was pleased with myself. Three kilometers later the speedometer etc stopped working. When I pulled the sensor out of the transmission the purple gear was mangled. The part of the sensor that it attaches to was damaged. I was able to buy a new sensor (Fiero Store) and another purple gear but my speedometer has not started working. When I probe into the transmission with my finger I can feel a gear inside the transmission that I assume the purple gear is supposed to mesh with. I can move it back and forth with my finger. I assume that the gear inside the transmission has become dislodged. I assume but I do not know. I have no idea how to determine whether the gear inside the transmission is the issue or how to resolve it, if that is the case. To troubleshoot the problem I hooked up the speedo sensor to a power drill to see if that part of the system works properly. When the speedo sensor is revolved with the use of the hand held drill the speedometer in my dash records speed. So the speedometer itself is OK. I believe that the sensor simply is not getting any messages through the purple gear. Has anyone out there encountered a similar problem before?

the gear u feel inside the trans is not suppose to move with your finger . its fixed to the shaft and only moved when the wheels are turning and then mates upto the purple gear at the end of the vvs. so if u can move it with your finger down in there and car not rolling theres your problem. and other idea also did u put the purple gear on the vvs the right way ? that would cause an issue also.

You lost old gear inside trans and didn't remove it then old gear can/will cause problems.

I think the gear will sink in oil when stopped but big gears can stir up whatever and oil.

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quote Originally posted by Scott2scott: the gear u feel inside the trans is not suppose to move with your finger . its fixed to the shaft and only moved when the wheels are turning and then mates upto the purple gear at the end of the vvs. so if u can move it with your finger down in there and car not rolling theres your problem. and other idea also did u put the purple gear on the vvs the right way ? that would cause an issue also.

Hello Scott2Scott. Thanks for getting back to me. I appreciate the input. I have been hoping for some kind of magical solution but I don't think that is going to happen. I believe that the purple gear is properly affixed to the sensor shaft. I believe what happened is that for whatever reason the gear inside the transmission has become dislodged from its correct location and will not mesh with the purple gear. So my car has no way of knowing how fast it is travelling, which affects other things. The ECM is not getting the velocity message so if it could maximize the fuel/air mix it is not getting the info to do so. I would really like to have a working speedometer but I see no easy solution. I do not have the skills or equipment to get inside the transmission to see if I can get that gear to stay in the correct location on the shaft. It does not seem practical to look for a replacement transmission with the gear in place, just to have a working speedometer again. There comes a point where the value of the repair is not worth the cost involved. If my engine would blow then I guess I would have to replace it and at that time maybe I could justify replacing engine and transmission. I can take a GPS with me on longer trips to have ready info about my speed, to avoid speeding tickets so the speedo thing is really just an inconvenience. I take it you have not heard of this particular problem before.