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Discussion Starter #1
I have a 2011 Sportsman 550. The fan quit coming on so I am having overheating problems. I ran 12v directly to the fan and it works. I swapped the fan relay with the same one in another circuit. That didn't change things. I keep reading about a 10 amp circuit breaker going bad, but I cannot find one. The ones I have seen in pics are located along a cable bundle behind the radiator. I do not see that on mine nor can I see one anywhere.

What am I missing? Where did they hide it?
 

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before you mess with the CB pull the sensor connector off on the cylinder head to confirm its not sensor.
 

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Discussion Starter #3
before you mess with the CB pull the sensor connector off on the cylinder head to confirm its not sensor.
I hooked up ohm meter to sensor and started out at 35.5 and as it idled it slowly dropped to 2.7 at which point I shut it off. Is that what it should do?
 

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sorry the fan should automatically run when the connector is removed.
 

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Discussion Starter #5
It did not run. Checked the voltage going to the fan with the plug off and get random voltage readings.

Just to be sure, I hooked the fan up directly to the battery and it runs fine.

What next?
 

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so the thermal CB is up by the rad on top. power comes from the fuse block hits the thermal CB then feeds the #30 terminal on fan relay.
 

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Discussion Starter #7
Found the thermal CB up under the left front fender between the frame and fuel fill tube. Replaced it. Still no voltage going to the fan with the temp sensor unplugged. I checked the voltage on the temp sensor plug while off and only shows 5 volts on the yellow wire. Doesn't seem right.

I am certainly open for suggestions for the next step?
 

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I don't have a print for a 550 but do have one for a 400 / 500 , I ssume the fan circuits are the same ?
If so ,with the key on , the red/white wire at the sensor should have 12 volts , check that out .
 

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Discussion Starter #9
The best i have is a print for the 2010 which I have attached. Tomorrow I plan on taking voltage and recording readings at all points, but I do know that I am only getting 5v on the yellow wire at the temp sensor with it unplugged. I am no electrical whiz (or I wouldn't be asking all of these questions), but I am starting to think that I may have a grounding problem or an ECM issue. .
 

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Your print is right , mine is different , Five volts is probably normal because your fan relay is controlled by the ecm ,
Things to check - , with the key on , you should have 12 volts + on the red/white wire on the fan relay on A7 and B7

With key on , unplug the sensor , you should have 12 volts across the relay coil A7 + and B6 -
 

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With the key on , sensor unplugged , run a piece of wire from ground or battery neg. to terminal B6 on the fan relay { orange / yellow } , does the fan come on ? { skin the og/ ye wire back a bit if you have to .
 

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That simulated the ground / negative from the ecm , check continuity of wire { og/ye } back to ecm , check plug at ecm for corrosion , if all is ok you need a ecm .
 

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Discussion Starter #15
Ohms start out at 0 and after a few seconds, climb up to 0.6. No visible corrosion at ecm plug or the contacts that I observe. Is that slight ohm reading a sign of a bad wire?
 

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Thats normal for the ohm reading , all signs point to the fan control portion of the ecm is bad , did you read the pm I sent you ?
 
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