I have a 2005 Yamaha Kodiak 400 4x4 so once the four-wheeler comes up to temperature the radiator fan will not turn on if I turn the ignition to the off position the radiator fan will fan will then turn on I was told it might be the ignition I bought the right ignition no change none of the wiring harness has been cut or messed with is there something else I am missing I would rather not run a toggle unless I have to

 

While I was looking into this more I found out my radiator Thermo switch is receiving power while my ignition is in the off position this is what is causing the fan to turn on when I turn the four-wheeler off but why is it receiving power in the off position instead of in the on position

 

What is considered up to temperature to you? My Raptor 660 I thought the same thing. Turns out the fan doesn't turn on until it hits like 220 degrees fahrenheit. At first to me that seemed really really hot but I guess that is normal. I never really get that hot unless it's just idling a bunch or in a low gear for a long time.

 

Well after I replace the head gasket on the four-wheeler I was starting it to bring it up the temperature in making sure my radiator was working good the radiator never turned on so after a while I just gave up turn the four-wheeler off as soon as I turned it to the off position to radiator fan turned on I turn the ignition back to the on position for radiator fan would turn off upon further testing I pulled the wires going to the radiator Thermo switch the wires are supplying power while the ignition is in the off position I turn the ignition to the on position the wires have no power going to them none of the wiring harness has been cut into

 

Can't see why you started two threads for the same problem, my answer is the same, get hold of the wiring diagram and trace the fan and temp sender wires back, my guess is either someone has altered the wiring or it goes through a relay which is sticking.

 

Merryman I apologize if I offended you by asking the same question in two different posts did not realize you're one of the sensitive types just trying to figure out what is going on with this four wheeler so that I may take my children camping and have a good holiday weekend I was hoping somebody else might have had this issue and could save me a little bit of time instead of me splicing open my entire wiring harness and tracing two wires

 

You don't need to open up the harness, a red wire going in at one end is the same wire as a red one coming out the other. If you can see an obvious place where the harness has been hacked, then take a look inside it there but otherwise it is easiest to work out what is going on, and how it is supposed to work, from the wiring diagram.

 

Here is what I was able to find as far as a wiring diagram for your atv. Is anything else getting power when your key switch is off? The key switch should ground all power when it is off. As merryman said it sounds like a relay sticking but definitely don't pull apart your wire harness because it shouldn't be anything in there shortening out. you want to make sure it is wired right. number 19 is your fan motor and you can trace it back from there.

 

This is the only thing that i was not able to find this circuit breaker is nowhere near the location of the showing so I'm assuming this is the problem nothing else is receiving power while the ignition is in the off position it is only the fan Thermo switch

 

Yamaha win the prize for the most unnecessarily complex fan motor wiring. Without the key it is difficult to trace back from Kyle's drawing. However it looks fairly straightforward as to how it is supposed to work. Br/L wire from ignition switch direct to switch 17 then switch 18 and the fan runs, (why two switches, one will be the thermal but what is t'other?) No matter, that wire has a break, or the fan would work with ignition on. Looks like, power is back feeding through the two relays 6 and 8 through fuse 9 with ignition off. Maybe it is supposed to, my car fan runs with ignition off until cool enough to switch off. This narrows down where the break is, as it is between where the Br/L wire feeds fuse 30 (otherwise whatever fuse 30 runs wouldn't work), and fuse 9.