2000 Magnum 4×4 oil cooling fan won’t shut off

Hello all,

I have a 2000 Magnum 4×4 that the oil cooler fan will not shut off. I have done some research and done some basic electrical testing using my fluke 87V meter. I have checked the resistance for the thermistor with it unplugged and got a reading of 1.307 k ohms. I have also checked it with key on engine not running and both yellow wires plugged in to the thermistor switch and got a reading of 312 k ohms. I contacted Polaris near my home and the shop foreman looked it up and at 77 degress f the resistance value should be 100 k ohms. I went to work and found a 100 k ohm resistor and tried plugging it in place of the thermistor and the fan still runs and light stays on. I also checked the ground coming out of the thermistor switch (with it unplugged) to frame ground and got an average reading of .2 ohms (which is to be expected I assume). I am completely lost with this problem. My neighbor has a 325 trail boss year model 2000 that is pretty well the same set up as mine. I guess I will try some testing on his unit since his works fine. Any help on this problem would be greatly appreciated. Thanks