I have an 08 trailblazer that thinks its hot and has the temp light on. My fan is running before I even start it. when I attempt to start the ignition clicks and the fan starts running. if I pull start it will start just fine but the fan is running and the temp light is on. my guess would be the temperature sensor but not sure where that sensor would be located.

 

The pic is for a 330 trail boss but the motors the same. Its part #12 that tells the fan to come on or off and temp light I believe. They call it a "thermister". OEM motorcycle and ATV parts from Honda, Yamaha & Polaris – Cycle Parts Warehouse

 

should be 2 wires hooked to it. if someone has a manual or ask a dealer what t he test specs are on it w/ an ohm meter to see if its good.

 

for anyone who reads this thread who has the same issue I learned its not the thermister, it's the power module this is just under the headlight. It's silver in color and it control anything that involves the ignition or power supply. Don't change the thermister if you turn the key off and the fan is still running. that would be the power module.