[bcsman]

So just got my 98 running after finding the timing had jumped. Everything back together and the front fender and grills done. Took for a nice drive of a few miles and never had the fan turn on. Most riding was at a decent speed so not sure if it was needed. Since buying last fall I actually have never seen it run so I need to investigate if the system is broke, don't want to overheat in warmer weather and do damage. The oil temp light does come on with the key but have never seen it come on during driving. Does that mean the thermal switch is good if it lights? I would like to test the fan itself and have read to take the blue wire off the thermal switch and ground it with the key on. If the fan is good it should run. The blades do spin freely so will see what I can come up with. Seems from doing some reading the fan is a common problem on these models.

 

[shadetree]

key on, ground blue wire to engine/frame for ground. if the fan motor is good ?, it will kick on. if it does ?, then this means your oil temp sensor switch is bad. yes the oil light comes on when you first turn the key on, then after a couple sec's, the oil light should go off.

 

[shadetree]

and you damn well better not over think this !!!!..rofl.

 

[bcsman]

and you damn well better not over think this !!!!..rofl.

hahahaha no electrical issues are in my wheelhouse of comfort, mechanical not so much. I made a copy of the wiring diagram from the manual if needed. Just gotta take the snow plow mount bracket off so I can get to it. Think I will leave off until I want to plow anyhow. Looks like kinda oily in that area, think maybe the bracket misdirects some oil when draining, we'll see. :wink

 

[bcsman]

Well crap, took the plow mount off and bottom frame cover off to get to the wire easier. That frame cover I'll bet has never been off. So got the wire off grounded it to the engine, turned the key on...nada. There is some clicking up where the fan control is so guess the grill and front fender come back off. There are things to check in the manual so will have to work that angle.

 

[shadetree]

Well crap, took the plow mount off and bottom frame cover off to get to the wire easier. That frame cover I'll bet has never been off. So got the wire off grounded it to the engine, turned the key on...nada. There is some clicking up where the fan control is so guess the grill and front fender come back off. There are things to check in the manual so will have to work that angle.

haha..i'll make this simple for ya bro !. remove the fuel tank, when viewing tank from sitting on bike, look on left side of tank, you will see the fan wires connectors, i'd start there !. you can run a 12 volt battery test with power straight to the fan, if it works ?, then you must trace power to the oil temp sensor. if the fan does not work ?, well..now ya gotta replace the fan motor...lol..

 

[bcsman]

Didnt remove the fuel tank, took the 2 connectors off the fan control. Then hooked my 12 volt battery charger up to the fan wires and fan comes on and runs fine. Checked continuity from the thermal switch wire up to the fan control and good. Getting 12 volts from the 2 inputs to the fan control wiring. So wiring seems to be good what few are involved. This pretty well narrows down to the fan control. That's what the manual points to also with the steps they give for fan not working with high oil temp.

 

[bcsman]

One more test, grounded light blue thermal wire, turned on key. Removed the 4P connector from the fan control and hooked my meter to ground and the pin on the 4P connector on the control where the blue wire would feed the fan. If things were working I should get 12 volts there going to the fan but nothing. So looks like a poopy fan control to me.....

Resistance from ground thru the thermal control is around 20K ohms, the manual says 10K ohms, but dont think that is the issue.

 

[shadetree]

sounds like a bad fan control to me.

 

[bcsman]

sounds like a bad fan control to me.

Yep and I don't think I did any over thinking on this one!!!

Yikes $120 for a new OEM...

 

[bcsman]

If I could find a used OEM might go that way, numerous used on Ebay but hard to say if Chinese or OEM...

 

[Goober]

Yikes $120 for a new OEM...

That’s not too bad at least you can buy them new lols.

oil light on my trx300 would not come on so I performed same test as you. FCU for a trx300 is hard to come by so I dried it out in the oven at 200F for 3 hours and it works. Although I noticed when the oil light comes on the fan kicks on til the light goes out. That’s new.

 

[bcsman]

Did one more test this morning. I jumped the pink fan fuse 12v on the 2P connector to the blue 12 volt 4P connector that feeds the fan. Then I jumped the lt blue wire coming from the thermal switch on the 2P connector to the green wire on the 4P connector for the ground. So basically bypassing the fan control completely and when the key is turned on the fan runs. Wanted to check that so I do need the fan control. I did have some fun tracing wires and voltage with the wiring diagram.

 

[shadetree]

Did one more test this morning. I jumped the pink fan fuse 12v on the 2P connector to the blue 12 volt 4P connector that feeds the fan. Then I jumped the lt blue wire coming from the thermal switch on the 2P connector to the green wire on the 4P connector for the ground. So basically bypassing the fan control completely and when the key is turned on the fan runs. Wanted to check that so I do need the fan control. I did have some fun tracing wires and voltage with the wiring diagram.

bahhhh...just spend the bucks...AND FIX IT RIGHT !, ( sigh ).

 

[retro]

Unfortunately, it sounds like your oil temp sensor is bad too, assuming that you measured resistance through it while at room temp as the manual states?

 

[Goober]

Did one more test this morning. I jumped the pink fan fuse 12v on the 2P connector to the blue 12 volt 4P connector that feeds the fan. Then I jumped the lt blue wire coming from the thermal switch on the 2P connector to the green wire on the 4P connector for the ground. So basically bypassing the fan control completely and when the key is turned on the fan runs. Wanted to check that so I do need the fan control. I did have some fun tracing wires and voltage with the wiring diagram.

Ahh you said you were gonna stop overthinking huh?

You can install a switch that will allow you to turn on the fan when you choose; but do you want to be a fan control unit?

Jk I did that too.

Check resistance of the oil sensor according to the manual. Both could be out of spec.

 

[shadetree]

Did one more test this morning. I jumped the pink fan fuse 12v on the 2P connector to the blue 12 volt 4P connector that feeds the fan. Then I jumped the lt blue wire coming from the thermal switch on the 2P connector to the green wire on the 4P connector for the ground. So basically bypassing the fan control completely and when the key is turned on the fan runs. Wanted to check that so I do need the fan control. I did have some fun tracing wires and voltage with the wiring diagram.

Ahh you said you were gonna stop overthinking huh?

You can install a switch that will allow you to turn on the fan when you choose; but do you want to be a fan control unit?

Jk I did that too.

Check resistance of the oil sensor according to the manual. Both could be out of spec.

from all that cash we saved him from doing all his own work , you would think a few bucks for a brand new oem fan control would be snapped up in a heart beat ??!!...lol.

 

[bcsman]

Always has to pass the mrs bcsman test...lol

 

[bcsman]

So got my fan control and installed. Tested out by removing the oil temp wire and grounding out with the key on. Before the fan control just clicked but now the fan runs like it's supposed to. I still am not sure if the fan will come on not sure how to test that. Maybe just start it and let it sit and idle? I did do a ride this afternoon but felt the oil return lines and they weren't very hot. I did a test before getting the new fan control a few days ago. Removed the 2P connector on the fan control to check resistance on the light blue wire to ground, had 17K. After riding for 1/2 hour or so shut down and rechecked the resistance and down to 3K so as the oil is warming the resistance is decreasing. Not sure where it needs to be to turn the fan on?

 

[retro]

The sensor should measure 10k ohms resistance at about 68 degrees F (spec is in the manual). Yours might be out of range judging by your comments about it. You can connect a 100k ohms potentiometer in parallel with the light blue sensor wire and bring that resistance back down within range (also provides further adjustment to allow the fan to kick on earlier, they let the oil get way too hot, when left stock) or spend the big bucks on a replacement and live with those excessive oil temps.

We are making a gizmo that solves all of those excessive oil temp problems Honda left on the table, right here:

https://www.hondaatvforums.net/forums/builds-projects-diy/128168-diy-cooling-fan-gizmo.html

If you're handy with electronics and soldering station (and fabbing plastic boxes) you can make one for yourself once we get them finalized. Or you can help us complete it... maybe ya got better ideas or knowledge that we don't yet.