2002 Buick Park Avenue mileage: 54,000. Car runs great. Speedometer does not always work. When it does not work and I am climbing a hill the "check Engine" light comes on. As soon as the speedometer starts to move again, the light goes off. Sometimes the light will stay on for 30 minutes, but when the speedometer moves, it goes out. Immediately car runs great. If I am going with traffic say 55 - 60 the speedometer reads 25 or so (sorta got to be careful about getting out at that speed Eh?) I get a code 24 from flashes on dashboard when asking computer about "check engine" deal. Problem is: the guys at the GM dealer say that there is no VSS on that year and model. And besides when I do find it, if I do have one on the car. Is it behind the speedometer or on transmission somewhere? Thanks for any help.
Your problem may be caused by the cruise control transducer. The speedometer cable from the transmission goes into the transducer and back out to the speedometer. It is more likely than not that the transducer is causing the problems you are experiencing. The vehicle speed sensor should be located in the back of the speedometer.