Water temperature gauge wiring?

[Guest]

I have a water temperature gauge with 3 terminals on the back when I was only expecting 2. They are + , - , & G. I was expecting to run a feed to the + and connect the temperature sender to the -. Help

 

[Guest]

Best guess

+ to positive

- to negative

G to sender unit

 

[Guest]

yep I agree for earthed engine