Mine stopped working on my rancher 420 because there was water in the connector. Unplugged it, sprayed it in both ends with contact cleaner and put some dielectric grease in it. Hasn't happened since.

 

my odometer quit workin on my foreman, pulled it apart and found that it had water damage, i just yanked it and replaced it with some offroad lights

 

Does the display still light up and the hourmeter still work? If so, first try cleaning the connector like Mudmat said. If that doesn't work, the speed sensor is probably bad. I had to replace the one on mine. If the speedometer doesn't light up and the hourmeter doesn't work, then it's not the speed sensor because both will still work when the speed sensor goes out.

 

Thanks for the info. it still lit up so i did what u guys said and cleaned the connectors. Works great now