Yep that the water temp sender. You can put that wire terminal to any handy ground source. Doesn't need to go to the battery.
If both gauges quit at the same time their power supply ( gauge voltage limiter ) is bad.
Thanks Redfish. I ran a wire from the water temp sender to the negative battery cable with the ignition key in the run position. Nothing on the cluster moved. Recently the fuel gauge and temperature gauge stopped working. The brake light on the cluster works as does the alternator. The oil pressure switch also stopped working. My inner tail lamps/backup lights also quit at the same time. I have double checked all fuses. They are good. What's up.
Last night I reached up behind the cluster and removed the voltage limiter. I think this limiter is bad. How do I test it to see if it's good or bad?
I've been told if the voltage limiter goes bad, it can fry the temp/gas gauge. Right now I don't know whether to buy a new limiter or send the cluster out for repairs. Advise welcomed.