:headache: My 2005 ATP 500 is overheating to the point the coolant boils out of the overflow. The fan and HOT lamp do not come on when this happens. The fan and HOT lamp do not come on when I disconnect the thermistor. The fan does come on when power is run directly to the fan harness.

I am thinking that since the fan and HOT lamp do not come on when the thermistor is disconnected, the problem may be the ECM (Sure Power box) rather than the thermistor. The red/white wire from the ignition switch is providing 12V as the RUN signal to the ECM.

Any suggestions?