1994 GMC Jimmy check gauges

Replace the instrument cluster. But that would change the actual mileage on my truck. Could we just disconnect the temp gauge or maybe something simple like a connection is undone?

The engine coolant temperature sender at right cylinder head dark green wire inputs the engine temperature to the instrument cluster.

You can try undoing it from behind the cluster or disconnect it from the sender but remember doing so might not activate the cooling fans if its specifically controls the fans and engine overheating will occur