1992 Pontiac Grand Prix Speed sensor bad? Speedometer "jumpy"

[leaveitto]

I have a 1992 Pontiac Grand Prix 3.1L with 151K miles. Recently, the speedometer has begun to slightly jump around the speed the car is actually going, which seems to be causing the cruise to surge, rendering the cruse control unusable. The speedometer otherwise functions normally. Does this sound like a bad speed sensor on the transmission? Or is there something else in the system that I'm unaware of?

I took a 700 mile trip this past weekend without cruise, and I'd like to have it operational!

Thanks in advance!

[Pickering Snow]

Well this one would really be a guess for me without a scanner hooked to the car to see if the speed is changing on it.

A bad VSS sensor which has a built in buffer could cause this there not that much money and worth a try a chaffed wire going to or from the sensor could give the same effect. Also depending on the trans either a Th125 3 speed or a th440 4 speed the tone ring could be shifting in the trans causing a interupeted signal has well.

[leaveitto]

Thanks! I'll see about replacing the sensor, and I'm hoping that the ring is not moving around inside the tranny. I guess my question was more of a "is there something really common that I've overlooked?" kind of question.

Thanks for the help.