1991 DeVille 4.9 - Speedometer/Transmission problems, help!

[amazingtrav]

Hello, I hope someone can help me out here.

The Car - 1991 SDV 4.9L FWD

The problem - About a month ago, I noticed a strange thing happening, sometimes, when I was stopped and then lightly touched the gas pedal, the speedometer would drop itself down to 0, stay there for a couple seconds and then wave its way back to my current speed. Durring the time the speedometer was at 0mph, the car would rev higher than normal. After the speedometer went back to the current speed, the transmission would shift up a gear, and the revs would come back down.

Recently however, the speedometer has stopped working all together, and stays at a constant 0, and the transmission is now not shifting past second gear, and the service engine light is on.

I've read some similar situations, however I haven't found anything leading to the exact problem. If needed, I can get the OBD codes from the computer.

Anybody have any ideas?

Update, here's the OBD codes the computer gave me.
P024 (E024) ..................................... Vehicle Speed Sensor signal to TCC
P052 (E052) .................................................. ..... PCM Memory Reset
P055 (E055) ............................... Closed Throttle Angle Out of Range [TPS]
P064 (E064) ................................. Cruise - Vehicle Acceleration Too High
P073 (E073) ..................................... Intermittent Coolant Sensor Signal
P075 (E075) ................................................ Intermittent VSS Signal

I'm hoping that the speed sensor is the one near the wheel that's easy to fix, and not in the transmission, anyone know?

[Ranger]

There are two speed sensors, VSS & input speed sensor. The input speed sensor is the $20 part, $2000 deep in the trans. The VSS is mounted on the right output shaft housing and is acessable through the right wheel well.

On second thought, that is for the 4T80E (Northstar), but the 4T60E (4.9) might be the same, not sure though.

[100]

I think a 4T60E is not that sophisticated (=one VSS, mounted outside). I still don't quite understand the need of that input speed sensor in a 4T80E. What does it do in there for you?

[amazingtrav]

Wow, that sensor was much easier to get to than I thought, and only ~$40

I reset the OBD Computer and took it for a drive after, the car is accelerating much much smoother than before, the cruise control is also working much better. I checked the computer after a drive and all of the codes were gone!

[cira]

Hey! I know your post is a couple years old, but I'm having the same problem. Did you ever get it fixed? If so, How did you do it? If it's not too much trouble, please email me at: pttpmusto@aol.com and share your solution with me. Be very grateful. Thanks!