Chevrolet: speedometer, 1997 chevy cavalier, chevy cavalier

Question
my seed odmeter flutuates from 10 to 30 miles rapidly it doesn't do it all the time , it could be weeks without it happening and then it starts up again and last a few days, I have a 1997 chevy cavalier, can you tell me what it could be? and approximatly how much to take care of the problem. I would like to have it repaired asp, my 16 year old is taking his driving test with this car and i would hate for him not to pass because of the vechile. thank you for your help                Lynda

Answer
Hi, Lynda, there a few things that could cause this problem. The connection may be carroded where it connects to the speed sensor (behind the engine on the transmission close to the right inner cv joint), it could be the speed sensor, or it could be the speedometer in the dash. It is hard to give you an estimate when we dont know for sure what the problem is. If it is the connection it would only be a few dollars, but if it is the speedometer it would be a lot more. I hope this helps you, if you need more info just let me know. Regards, Keith.