My 96 Cherokee has had a problem recently where if I go mudding and hit deep water the rpm gauge goes out for a while then comes back once everything is dry. Last time when it came back the gauge would go up and down whenever I put on my right turn signal (left signal didn't do it) and then it worked totally fine the next day. It runs fine and everything other gauge works and it only happens when something gets wet. Is there a sensor for the rpm gauge I should look at or what else do you think it could be?

 

since it blinks when you hit the turn signal, i would think something else got wet, or is shorting across until dry. i am not sure where that signal is picked up on jeeps but check your coil and make sure the wires are plugged in well and clean. maybe also check the plug to the distributor for cleanliness and good connection

 

The circuit for one component that has a bad ground is seeking a ground through another component.