Truck started overflowing coolant when i parked it last night, could hear it boiling when i popped the hood. The gasket on the cap is shot so i think it sucked in air. At any rate the PO was not great at maintenance so I am going to replace thermostat and some other stuff. My temp gauge does not register so i am going to start with a new sensor but when i look at the connections I cant figure out which is the sensor to the gauge, i have never seen so many things plugged in to the system like that! Can anyone tell me which is the one to replace?