Hey GIL :waving:Welcome to the best Goldwing Forum on the net. :clapper: I dont know anything about Temp Gauges, :crying:but dont panic one of our "Gurus" will be along shortly to help you out. :clapper:
Welcome to the forum GIL. Our official forum welcomer, Redwing is on the ball tonight.
The fan and temp switches are two seperate items and both of them can be found on top of the thermostat housing (top of engine behind the radiator fan). Not the easiest to get at, but now you know where they are. The temp switch is the one behind the fan switch. You'll need to remove the lower fairing covers for access.
The thermostatic switch for the fan and the temperature gauge get their power from two different sources. The fan runs on the 12V system but the temp gauge and gas gauge both operate from a 7V supply. If your gas gauge is working it is probably the wiring to the temp sensor or the sensor that's the problem.