I have a 98 400 Prairie. the engine runs great, but the radiator fan won't kick on. The temp light comes on after a few minutes of riding, so I have to shut the quad down. I tested the fan by straight wiring it to the battery and it runs fine. How do I get the fan to kick on, or is there a sensor for it? Thanks.

 

There is a fan switch on the side of your raditator about two inches below your radiator cap. Try to jump this switch out and see if that makes your fan come on.
I am not sure how you wired the fan up straight. Did you use all new wires or some of the factory wiring . Mine has a inline fuse next to the fan you may also want to look for and check it. My owners manual shows a picture of my inline fuse.