I have tried everything! I have tried new thermostat, temperature relay switch, air cleaner, and line from air cleaner to radiator. The overheating check engine light came on; however, it no longer comes on. The fan comes on after riding it for 10 to 15 minutes. It turns off when I turn the key off. If I restart the atv right away the fan comes on again and doesn't shut off. If anyone has some advice out there, I sure would appreciate it! Thanks for reading.

 

thats weird. you said you replaced the sensor in the engine. thats what turns on and of the fan. no bad connections or anything.

 

what year is your? most all the fan problems i have seen were caused by the module that is a recall. PCM MODULE

 

I am having the same issue with my 2004 sportsman 500 HO. When I was riding the Hot light came on for a minute or so and it cut off. The fan was running before it shutoff and now the fan runs all the time as long as the battery is hooked up. I aslo can't get the unit to crank although it will turn over just fine. The engine was cool to the hand so I really don't get it.

 

Is your rad clean of baked on mud. The top half of the rad is harder to clean than the bottom half.

 

My 2004 Sportsman 400 had the same problem shortly after I got it. I called the dealer and they replaced the PCM Module. Apparently, there was a recall, they knew what the problem was immediatly.

 

yea that modual does about a million differnt functions so it wouldnt surprise me. it even effected capers lights on his bike.