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Apex over heat light, fan not coming on

RacerDave

Expert
Joined
Feb 20, 2007
Messages
401
Location
North Central Illinois
Overheat light came on from low snow conditions. Fan would not come on. Shouldn't the cooling fan come on before or with the over heat light? The fan will work by pulling the relay and jumping the correct terminals. The relay works fine on a bench test. Does the temp switch trigger the fan relay through the ecm? Is this temp switch normally open till it reachs xx temp and then the relay gets closed turning on fan, or does the temp switch have a variable resistor sending a signal to the ecm and then the ecm triggers the fan relay at xx temp?
 

I'm can't answer most of your questions but my fan comes on before the warning light. On hard pack or plowed logging roads I can feel my right foot & shin warmup which I assume is from the fan kicking on.
 
ricerocket said:
Overheat light came on from low snow conditions. Fan would not come on. Shouldn't the cooling fan come on before or with the over heat light? The fan will work by pulling the relay and jumping the correct terminals. The relay works fine on a bench test. Does the temp switch trigger the fan relay through the ecm? Is this temp switch normally open till it reachs xx temp and then the relay gets closed turning on fan, or does the temp switch have a variable resistor sending a signal to the ecm and then the ecm triggers the fan relay at xx temp?

Yes, the fan comes alive before the light.

Here an old posting with some numbers:
http://www.ty4stroke.com/viewtopic.php? ... highlight=
 
A dealer would be the ones to call..

I would guess the coolant temp sensor on the engine would send a signal to the computer and the computer would turn on the relay for the fan..
 
Does the temp sensor give the ecm linear readings or is it a switch that is normally open till it reachs a certain temp and then closes sending the ecm a signal?
 
over heat

follow the wire harness for the fan up under the head light i believe. look for the connector and make sure it is plugged in.my 06 was unplugged and that is what the dealer found when i took it in under warr.
 
My guess is the temp sensor went bad or the wire to the computer from the temp senser is broken..

Thats just a guess..

Do you have any warranty? if so have the dealer check it.. they might have the specs for it..
 
Warranty ended on 2-15-08. I'm sure someone here has the answer I need. If I can find specs on the temp sensor that would help. I have a shop manual on CD, but can't find my answers.
 
R. R. i have not seen the schematic for this system on this sled, but on other brands when I have installed a temp gauge the original sensor was just an open closed sensor to run the light and I had to install a veriable sensor to run the gauge. It would make sense that Yamaha would have a similar set up. Check with guys that have installed a temp gauge and if they replaced the original sensor then it is pretty for sure that the original is just open closed with two settings, one for fan on signal to ECM and one for light on signal.

Hope this helps
 


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