Long time reader, first post.
I have read every post I could find on overheating sportsman and am more confused than before.
My 2004.5 500sp has overheated once now. No fan, hot light came on and coolant spewed mostly from reservoir cap, but the area under the filler cap was a little wet also.
After, radiator only needed a little coolant and I had to refill overflow. Tried again with same result: no fan: overheating, but no hot light. Unplugged sensor on left side of engine and turned key on. Fan ran and hot light came on.
No crazy electrical issues pointing to ecm problems. Radiator seems clean, bottom hose gets hot when running.
Have read to replace a sensor on top of radiator (can't find), or replace a sensor on engine ( I assume what I unplugged), or replace the fan switch (no idea where that is), or this is an ecm problem.
Any suggestions? Deer season is approaching here in Mississippi and I am getting nervous about my ride.

 

hmm... I know some models had 2 temp switches ( i dont remember which years), one to control the fan, and one for the dummy light. If the fan came on when you unhooked that then atleast you can rule out fan or electrical connections to the fan are bad. Unfortunately in that case i would swing more to an ecm issue as i have heard of that problem before...

one case: http://forums.atvconnection.com/pola...ue-solved.html

However if time is of the utmost importance and you need your wheeler working you could always wire a temporary relay with a stand alone switch to operate the fan whenever you wish... until you figure out the root of the problem

 

i believe the temp-fan switch is on the right side radiator tank

 

My '03 600 has one sensor that controls the fan and has a seperate sensor on the cylinder that controls the "idiot" light. The thermal sensor swith has an eletrical plug in near the top of the radiator and also connects near the bottom of the radiator. On mine if that sensor is disconnected and hot wired and the fan kicks on you know the sensor is bad. The sensor on the cylinder head (single wire) only controls the idiot light. I would check with the dealer if you don't get response right away from someone here. I think they would be able to tell you what is wrong.

 

Thanks for responses.
I think the sensor on the cylinder is bad. When unplugged, the fan comes on and the light comes on.
I don't see a sensor on the radiator. The parts manual doesn't show one for the 2004.5, but there is one on the 2004 model radiator.

 

Try a new sensor, cant me too much money, but it doesnt necessarily mean the sensor is bad. when you unplug it it means the ecm is getting no signal at all. A possibility is that the sensor is bad and sending bad info into the ecm though. Did you read that other post i linked to about the 04.5? has your symptoms.