I'm assuming you mean a chrysler / dodge neon?
I used to own a '96, and I had an intermittent issue with the speedometer. Sometimes it would work, sometimes it wouldn't, and smacking the dash would sometimes make it work again.
I removed the gauge cluster and found a cold solder joint on one of the connections to the PCB. After reheating the joint and adding a little extra solder, the gauges worked fine ever since.
Hope this helps!