Assistance diagnosing failing cooling fan - Honda Rincon Forum : RinconRiders Honda Rincon Forums
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post #1 of 12 (permalink) Old 10-15-2016, 08:42 PM Thread Starter
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Assistance diagnosing failing cooling fan

Hey guys,
I was up outside of Georgetown, CO last week, and my coolant got so hot it was spewing out of the overflow valve of my reservoir. I have a 2003 Rincon 650. My temperature warning light came on. I obviously turned it off, let it cool, then coasted downhill back to my trailer. Thankfully it was only 40 degrees up in the mountains.

I've gotten it home, and I'm trying to diagnose the issue. My fan's 10 amp fuse was blown, so I checked the fan for rotation. It had a piece of rubber that has jammed in the fan . I removed the rubber and replaced the fuse, it now spins freely and easily.

Unfortunately this hasn't appeared to have fixed the issue. The fan doesn't turn on, even when I let it idle for 20 minutes. Given that it was 80 today in Denver, I would have expected it to come on, and the engine gets quite hot. I flushed and replaced the coolant as well while I was working on it.

I've been using this thread as a reference.

https://www.rinconriders.com/22-maint...working-2.html


I've done the following.

Checked the sensor in the bottom of the engine. The wires appear to be connected to the sensor, but they're in a heat shrink. Do I need to cut the heat shrink off to get a better look at them?

I've used my voltmeter to test this connection right behind the radiator

https://www.dropbox.com/sc/mv2q2a1a6...sqyAsZ1MCf8lca

Is that the wire that's referenced in the fan not working post? If so, I connected the blue wire with an exposed bolt on the frame. My voltmeter registered 14.5 volts, and the fan did not come on. If this is the right thread, I'm assuming it would have activated the fan motor if it was working correctly?


I also completely unplugged the male end of the plug. I tested the voltage flowing through both connectors on the female side from the control module, and it registered 0, so it seems it's not getting current. This means either 1) it's not hot enough for the sensor to activate, or 2) the sensor is also broken.

I'm struggling to isolate the problems individually. Can anyone offer a suggestion to test the fan independently of the sensor? I know both could potentially be broken, but it would be nice to be able to test each one to verify.

Thanks,
Todd
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post #2 of 12 (permalink) Old 10-16-2016, 02:52 AM
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Simply connect a 12v battery to the two wires going to the fan couple of test leads or bits of wire should work. If fan works then it's either the thermo switch or lack of power supply.
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post #3 of 12 (permalink) Old 10-16-2016, 08:14 AM
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your talking about the oil sensor at the bottom rear of the engine. The Thermostat switch is by the carb on the left side of the motor (as you sit on the quad, left side)
If the "oil sensor" wires break, at idle, after aprox 5 minutes the light will come on indicating overheating (motor is not overheating, no signal from switch causes ECU to turn it on). If it is good the light will not come on after 6 minutes.

Your temp sensor is most likely the cause.
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post #4 of 12 (permalink) Old 10-16-2016, 01:46 PM Thread Starter
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Thanks @TaH and @Oilcan. Just so I'm clear, this is the sensor you're saying I need to check, assuming the fan doesn't turn when it's directly wired to a battery?

https://www.dropbox.com/s/3s4zgv470g...%20AM.png?dl=0

Thanks,
Todd
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post #5 of 12 (permalink) Old 10-16-2016, 03:15 PM Thread Starter
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Also, I disconnected and grounded the wire with my meter when the power was on. It's only getting 4.5 amps through the system when grounded. Is that expected? It didn't turn on the fan, so I'm thinking either my ECM is having problems of the fan motor is shot. It wouldn't surprise me if it is the fan motor, since it something was lodged in there.
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post #6 of 12 (permalink) Old 10-16-2016, 08:35 PM Thread Starter
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So I'm thoroughly stumped here....

I connected my fan connectors up to a marine battery I have. It kicked on no problem, so I know the fan motor is working correctly when it gets power.

I *believe* I've taken the correct wire off the correct sensor and then grounded it, which should turn on the fan when my ignition is on. However, the fan doesn't come on. I've attached a picture of me grounding it with my voltmeter, the voltage I get seems really odd. It's 4.93. Given that it's a 12v DC system, I was expecting 12-14v. When I test it's resistance, I get 1, so it appears the circuit is not shorted anywhere.

What else can I check here guys? I'm really at a loss. My next thought would be to ground the line out on the sensor, then test if the female end of the fan motor harness is getting power. Outside of that, I'm completely stumped. Thoughts? Attached is my picture. Can someone please verify I'm shorting the line attach to the sensor correctly? This is the deepest I've ever been into fixing my Rincon. I've replace the choke line and the neutral sensor switch, and that's it. It's always just worked!



Thanks,
Todd
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File Type: jpg IMG_5885.jpg (72.4 KB, 14 views)
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post #7 of 12 (permalink) Old 10-16-2016, 09:32 PM Thread Starter
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So after all of this work, it appears to have simply been a problem with one of the lines on the female end of the connector. The connector wasn't seating properly. I pushed the pin farther in, electrical taped it, and now it works when I short out the sensor wire!

However, the fan still isn't turning on under normal operating conditions. The engine gets pretty hot, and it's not turning on. What sensor causes the fan to turn on normally?

I noticed when I short the sensor @Oilcan referenced near the carb, it also turns on my temperature warning light. Since this came on when I was riding, I'm assuming this sensor is working correctly. I want the fan to come on when the engine gets hot before it hits a critical temperate.

Thanks,
Todd
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post #8 of 12 (permalink) Old 10-17-2016, 07:57 AM
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Quote:
Originally Posted by Todd Nine View Post
Thanks @TaH and @Oilcan. Just so I'm clear, this is the sensor you're saying I need to check, assuming the fan doesn't turn when it's directly wired to a battery?

https://www.dropbox.com/s/3s4zgv470g...%20AM.png?dl=0

Thanks,
Todd
do the boiling water test on your thermostat. It could also be stuck closed. The complete testing of your cooling system is chapter 6 in your service manual. A good read!

03 Green Rincon

Last edited by Oilcan; 10-17-2016 at 08:00 AM.
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post #9 of 12 (permalink) Old 10-17-2016, 02:07 PM Thread Starter
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Hi @Oilcan,
Quick question before I disassemble my thermostat. My radiator gets really hot, so I'm pretty sure the coolant is flowing through it. If my thermostat was stuck, wouldn't my radiator stay cool?

Last edited by Todd Nine; 10-17-2016 at 04:42 PM.
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post #10 of 12 (permalink) Old 10-17-2016, 02:41 PM
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There is a small bypass on all engines to allow some coolant to flow. If the thermostat is not opening fully your radiator will still get hot but not allow enough flow to cool the engine as it should. Do what Oilcan said and check your thermostat.
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