Speedometer stop working 1994yj wrangler

All of a sudden the mileage indicator stop working but the speedometer gauge is funcional. Anyone knows if I should change the whole tach or perhaps a speed sensor? Thanks!

you could have a bad sensor, but I had a similar problem with my 93yj when I bought it, and my problem ended up being a bad spot in the printed circit behind the guages.
the bad spot was causing the spedo to not get power. I was able to fix it by just using a short piece of wire and jumping from the tach power terminal to the spedo power terminal.
if you pull the guage cluster out, you will see the printed circit on the back side, just trace all of the "wires" in it to see if any of them have bad spots.