how many miles on the machine?you might have a vapor lock in the cooling system,this machine has a very good cooling system when its working properly.to bleed the cooling system you have to raise the front of the machine off the ground and remove the cover under the front rack to get to the radiator cap.remove the radiator cap and refill the radiator with antifreeze,start the machine with the radiator cap off and run the machine for a few minutes add antifreeze reinstall radiator cap ,run the machine until the cooling fan turns on and goes threw its cooling cycle,if the cooling fan does not turn on than you nhave to change the thermo switch on the radiator and rebleed the cooling system.

 

Yes this a common issue. The oem switch is costly, there is a fan switch off of a toyota that most everyone uses , me inclusive, but i can't find the number that i used. hopefully someone will chime in . All that needs done is,modifing the terminal ends of the switch , to fit your plug-in

 

The fan should actually come on automatically if you unplug the sensor. If it doesn't,(you said you had to hot wire the fan) then your problem is most likely in the ecm. Only way to check it is to have the dealer hook it up to the computer, and even then, it may not show anything. Sorry to bear the bad news. That happened to my friends rzr a couple months ago.

 

All i did to my 02, was wire the fan to a switch, i fire it up, after a few minutes, i flip the switch fan comes on, and ive had no problems.