Hot light is controlled by a single lead hooked to the sensor on the back part of the head.The thermostat switch is the one on the radiator. Another thing that can cause overheating before a fan can kick on is if air is in the system. In front the the hot light sensor on the head is a 10mm bleed screw. Open it for a minute or so to remove any possible trapped air. To test if the fan motor is ok is to either jump the two connectors on the radiator sensor or run 12 volts directly to the fan. If the fan works,it's usually the radiator sensor shorted out. It completes the ground path for the fan to kick on.Coolant needs to be full to keep these sensors from shorting out. If the fan motor is the problem you might want to check into the aftermarket fan I linked to.