I have a computer controlled quad, 305 5 peed, 1986 IROC Z. I just replaced the cooling fan relay sensor on the passenger side head to make the fan come on. There is another sensor (one wire) on the driverside head between #1 & #2, is this the gauge sensor? There is also a sensor in the top of the thermostat housing with 2 wires, what is this one?

 

On the drivers side is the one for the guage.