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Good work—i like to see Resto back to original configurations.
I wired up an FCU bypass fan but used a handlebar mounted switch
 

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Discussion Starter #3
Good work—i like to see Resto back to original configurations.
I wired up an FCU bypass fan but used a handlebar mounted switch
A handlebar switch is a better idea than the toggle switch on the side panel. Im curious to see if how the fan comes in in the factory form. Ill be riding it tomorrow!
 

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Check the service manual under oil overheat system—you can isolate the oil temp sensor.

remove the sensor terminal and ground to the footpeg—if fan comes on then you’ll know power getting thru the system.

resistance check the sensor at ambient.Most sensors fall out of range and will not activate the fan early enough!

Temp check them in hot oil. The sensor should read betw .95 and 1.1 KOhm at 200F.
 

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Check the service manual under oil overheat system—you can isolate the oil temp sensor.

remove the sensor terminal and ground to the footpeg—if fan comes on then you’ll know power getting thru the system.

resistance check the sensor at ambient.Most sensors fall out of range and will not activate the fan early enough!

Temp check them in hot oil. The sensor should read betw .95 and 1.1 KOhm at 200F.
Thanks you for the info! Very helpful! Im going to test the ohm reading tomorrow.
 

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All of my sensors are out of range—too high resistivity—fan will not turn on soon enough. So I installed a manual switch
 

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Could a resistor be added across the terminals to effectively lower the resistance of the sensor? It would need to be pretty high to work.
 
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You have a D model—those sensors may still be available.

yes i put a 10 KOhm variable resistor in parallel with the sensor—but then trying to program the circuit resistance to the overheat temp resulted in 0.95 Ohms at 140F. And the fan never came on. So I removed the resistor
 

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I just went for a hard ride, fan never came on but the temp sensor is reading 1.6 ohm. Grounding the blue wire makes the fan turn on so I know the system is working. Thoughts?
 

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You have power to the fan that’s good.

your resistance values aren’t right tho. The manual lists the values in KOhms
 

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Yeah I need to get my temp gun and do some more testing. So I'm looking at a faulty sensor more than likely.. I found the part on partzilla but its a single connection sensor like the new style honda temp sensors. Will that work? Makes sense because it just needs to make a ground connection via the engine.
 

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I’m pretty sure yours is a single wire. If you can one for your model from Partzilla then that’s great
 

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Interesting discussion. One post states .95 to 1.1Kohms. I mistook that as being 950 - 1,100 ohms.
I ran across a typo in my TRX300FW manual in troubleshooting my no start condition a few weeks ago.
 

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Mine is a dual wire unfortunately. I don't know what the other wire does though.
Oh you have the same design as mine, the 86-87 TRX350A. I have a single-wire sensor out of my TRX300 i will try putting that one in later today.
 

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Check the service manual for your quad—under oil overheat. Here I’ll ref the TRX350 manual. You can try this by suspending your sensor in a heated pan of oil

The ambient state of the thermistor is ~8.5 to 10.5 KOhm.

Between .95-1.1KOhms (200F) the fan should come on but the oil light remains off. The manual doesn’t say this explicitly but this is what occurs

At ~231Ohm the fan is already running but then oil light will come on.

if your sensor’s ambient resistance has shifted upward the whole curve shifts upward.

151012
 
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