ORIGINAL: idodirt

No, the Thermo Switch is not the Thermosensor. They are two separate things relating to a similar area of the bike. The only function of the Thermo Switch is to monitor the temperature of the radiator. When the radiator gets hot enough, then the Thermo Switch closes and turns the fan on. Realize though, that the radiator has to get hot. If it doesn't get hot, then the fan won't come on. Now, in order for the radiator to get hot, water has to circulate through it, hot water that is. When you start your engine, water doesn't start circulating through the radiator. Only when the engine warms up and the Thermostat opens does the water circulate through the radiator. It takes a while for enough hot water to be circulating through the engine and radiator before the Thermo Switch trips and turns on the fan. Now, the job of the Thermosensor is to monitor the engine temperature and make the temperature gauge move the needle that tells you whether the engine is hot or cold. If you take the lead off of the Thermosensor(it's located justabove the CCT and a little to the inside. It's visible from above when the tank is off and you look between theright frame and the airbox)and turn the key on, the temperature should read at the bottom of the scale on the cold side. If you touch the lead to the frame while the key is on, the gauge should read all the way to the hot side of the scale. Don't do this for more than a few seconds or the gauge could be damaged.

ORIGINAL: idodirt

If the thermosensor were to "Short", it would damage the Temperature Gauge by making the needle peg at the high end. Not sure what type of damage or how it would appear. That's about the only thing that I think that would cause both to fail. If the Thermosensor is just out of spec, then when you turn the key on, it would read improperly. Does the needle on the Temp Gauge go all the way down to cold when the key is off ? If it's just the Thermosensor it's only around $35, so not too bad.