Doing a resto on my 205cc Scoot. I am having issues trying to figure this one out. Cooling system works fine, both hoses get warm and fan turns on when it needs to. Flushed old coolant and put new. I've replaced the temp sensor located near the carburetor, but the temp gauge never moves. When I did replace the sensor, no coolant came out, but when I ran it, coolant came out the sensor hole (water pump functioning).
I've also tightened down the 3 wires at the gauge itself and even loosen/tight movement while watching the gauge to see if it was a bad contact. Nothing.
Found a post to test the 3 wires. Black is Pos. There are 2 greens coming out of my gauge, one is showing battery voltage and the other climbs as the engine warms up. Looks like my Chinese Temp Gauge is fubar.
As I understand it the sensor provides a variable, heat sensitive ground, so it makes sense that one would change as the engine warms up. The other one, I would assume, is the basic ground for the gauge, reflecting the 12v coming in on the positive wire. So, long and short, all that strikes me as kosher, so I'd tend to agree the gauge itself is fubar. That, however, from a rank amateur about such things.