The gauge circuit board is notorious for bad connections causing one or more gauge and lights not to work.
Remove the gauge cluster and each gauge. Clean the contacts on each gauge and circuit to each gauge. Check for damaged circuits on the circuit board (more like a film, really).
Pay close attention to the wire harness/PC board connection, clean well.
Reassemble and test. It is not unusual to have to do this several times to get everything working (had to do mine 3 or 4 times before everything worked)
Rust free YJ for sale. Need more room in barn.