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Old October 3rd, 2019, 02:22 PM   #1
Zolland
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Fan doesn't run after some maintenance (had to snip some wires). Diagnostic tips?

Hey all!

So I recently adjusted the valves on my 250, so far everything seems to be in order EXCEPT for the fact that I haven't noticed the fan turn on at all. I'm not entirely sure when it should turn on, but I definitely noticed it on pretty often before (it was working perfectly before).

I double checked and the fan is plugged in nicely.

I think the problem might be coming from some wires I snipped. The previous owner had installed grip warmers (don't see any logic there, but ok lol) and decided to make it impossible to take off the front fender without having to cut wires. I only cut wires that lead to the grip warmer control unit/grips, but maybe this could be it? Seems a little unlikely to be, but also the most likely thing I can think of as I didn't mess with any other wires. Maybe there is a temperature sensor that isn't working now?

I want to attack this problem, but I lack the knowledge to properly diagnose the issue. What is the best way to go about this? Is there any way I can manually turn on the fan so I don't have to turn the bike on and ride around to test it? Are there any common ways to test these types of issues? Are there common mistakes that could cause this type of problem?

Thanks!
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Old October 3rd, 2019, 02:58 PM   #2
DannoXYZ
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Fan thermoswitch (sensor) connected on left side?
Fuse #7 conducts electricity?
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Old October 3rd, 2019, 04:39 PM   #3
Zolland
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I could check the thermoswitch sensor when I get home. What's the easiest way to check if the fuse conducts electricity?

Edit: Also, how exactly does the thermo sensor work? From what I'm seeing online it is measuring the temp of the coolant. I may have leaked a lot of coolant which I'm going to replace tonight. Is it possible that the liquid isn't rotating enough and isn't reading correctly? Possible that the engine just isn't warm enough for the fan to turn on? Is there any way to force the fan to turn on to make sure it isn't broken?
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Old October 3rd, 2019, 09:06 PM   #4
DannoXYZ
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Best way to test fuse is to measure resistance (ohms) across legs. https://learn.sparkfun.com/tutorials...ing-resistance



Thermoswitch is like regular switch, except instead of using your finger to flip it on & off, it's done by coolant temperature. At low-temps, switch is open and no current flows. At high-temps, switch closes and current flows to turn on fan. Like with fuse, connect multimeter to measure resistance across terminals of thermoswitch. Measure resistance at room-temperature. Then put thermoswitch in pot of water and bring to boil. Measure temperature where resistance changes from previous state. Thermoswitch needs to be immersed in coolant to work.



1. You can test fan-operation by unplugging connector from thermoswitch. Then use short piece of wire, bridge two terminals inside connector. Does fan turn ON (with key ON)? If NOT, you've got two possibilities:

2. fan BAD? Disconnect fan connector. Using test-leads, apply +12v & ground to fan. Does it spin? If YES, you've got problem with wiring between fan and battery.

2. wiring BAD? If fan spins when power applied directly, but NOT when thermoswitch plug is shorted, then power is not making it from battery to fuse to thermoswitch connector. Test by tracing flow through fan-circuit. Measure voltage at following points:

- battery +positive terminal
- white wire leaving starter-solenoid
- white wire entering fuse-box
- white/blue wire leaving fuse-box (after fuse#7)
- white/blue wire entering thermoswitch-connector
- (short two terminals in thermoswitch-connector, then continue measuring voltage)
- blue-white wire leaving thermoswitch-connector
- blue-white wire at fan connector

Where +12v disappears will point to problem between there and previous test-point.

Last futzed with by DannoXYZ; October 8th, 2019 at 08:21 PM.
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Old October 8th, 2019, 06:58 PM   #5
Zolland
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Wow @DannoXYZ thank you for the detailed response! Sorry for the delay, I've been sick and haven't been able to make progress the last couple of days. I bought a multimeter, but have a few clarification questions.

0) Do I remove the thermoswitch just by unscrewing it? Will this cause coolant to poor out if I don't empty all the coolant?

1) What do you mean "bridge two terminals"? Sorry for the basic question, but I'm lost on the terminology here.

2) Do you have a suggestion for getting +12v? I haven't tested some of the rogue wires so I may have a live wire somewhere that was leading to the grip warmers (not good, but can fix that later), but if not is the best bet to go buy another battery?
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Old October 8th, 2019, 08:19 PM   #6
DannoXYZ
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Quote:
Originally Posted by Zolland View Post
0) Do I remove the thermoswitch just by unscrewing it? Will this cause coolant to poor out if I don't empty all the coolant?
Yes, drain it into bucket. Then you can filter it through old T-shirt and pour it back in at end. Why are you losing coolant? Fix that problem too.

Quote:
1) What do you mean "bridge two terminals"? Sorry for the basic question, but I'm lost on the terminology here.
When you unplug connector from thermoswitch, you'll have connector with two metal terminals inside.



Make short jumper wire with bare ends.



Plug it into connector's metal terminals to send current from one across to other.



With key ON, this jumper should activate fan (if it's operational). Also measure for voltage on blue/white terminal of this connector and there should be +12v power if wiring is correct.

Quote:
2) Do you have a suggestion for getting +12v? I haven't tested some of the rogue wires so I may have a live wire somewhere that was leading to the grip warmers (not good, but can fix that later), but if not is the best bet to go buy another battery?
You can get some test-leads with alligator clips. Then get power directly from battery to test fan.
Or you can also clip to auxiliary power-connectors near front.

Last futzed with by DannoXYZ; October 9th, 2019 at 03:13 PM.
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Old October 8th, 2019, 08:33 PM   #7
DannoXYZ
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When testing circuits, idea is non-invasive and non-destructive inspection. Have everything plugged in as normal and don't change anything (or you may introduce additional errors into system). Back-probe connectors by touching metal-terminals inside connectors to measure voltage. Some people tear everything apart and wonder why things don't test correctly.



To test fan's power-circuit, use alligator-clips to connect multimeter negative-probe to negative-terminal of battery. Then use positive-probe to measure for voltage at various points of circuit (key ON):

- battery +positive terminal
- white wire leaving starter-solenoid
- white wire entering fuse-box
- white/blue wire leaving fuse-box (after fuse#7)
- white/blue wire entering thermoswitch-connector
- (short two terminals in thermoswitch-connector, then continue measuring voltage)
- blue-white wire leaving thermoswitch-connector
- blue-white wire at fan connector

- also measure resistance between fan-connector's black/yellow wire and chassis-ground.
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Old October 15th, 2019, 07:14 PM   #8
Zolland
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Finally got time to test all of this! The results seem fairly conclusive and pinpoint the problem, but I find the conclusion a little hard to believe...

Quick question before getting into it, when testing the fuses I would get a reading of "0.00". Is that correct?

As for other the tests, I followed your steps and every point of failure you suggested tested perfectly with +12v but the fan wasn't turning on. I thought this was odd and decided it must be the paper clip I used (maybe couldn't let enough power through?). I actually have a live wire from the wires I cut and fed it to the other side of the thermoswitch connecter and the fan came on!

Here's a visual

To sum it up (and think out loud here) there is power feeding into the switch, but no power comes out. If power is applied directly to the other side of the connecter, the fan comes on. So this seems to imply that the thermoswitch is faulty, correct? It just seems weird that it would just so happen to break just when I also happened to do a bunch of work and also cut some wires... I'm a bit skeptical, and think maybe I messed something else up somewhere else but if you also think this test was conclusive then I'll go ahead and order a new one!

Thinking out loud again, could it be possible that coolant isn't rotating correctly and is causing the sensor to never read the correct heat? Is there any way to test this? I warmed up the bike and put my hand next to the sensor and it was super hot though.

Here is some background in my situation, and the source of my skepticism. I had to snip these wires and remove these connections to get the front fender off. Can't rememebr if the two big rubber females ever had anything connected.

Snipped Wires

Last futzed with by Zolland; October 16th, 2019 at 08:55 AM.
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Old October 16th, 2019, 12:10 AM   #9
DannoXYZ
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Quote:
Originally Posted by Zolland View Post
Quick question before getting into it, when testing the fuses I would get a reading of "0.00". Is that correct?
Yes, that's correct. Zero-ohms, no resistance, perfect conductivity. Good job testing!

Quote:
As for other the tests, I followed your steps and every point of failure you suggested tested perfectly with +12v but the fan wasn't turning on. I thought this was odd and decided it must be the paper clip I used (maybe couldn't let enough power through?). I actually have a live wire from the wires I cut and fed it to the other side of the thermoswitch connecter and the fan came on!
I'm not sure what you did here. You originally bridged connector with paper-clip? And that didn't turn on fan? You skipped step:

- Did you have +12v at white/blue wire leaving fuse box?
- Did you have +12v at white/blue wire where it entre thermoswitch-connector?


However, if you were low on coolant and thermoswitch wasn't immersed in coolant, it would not turn fan on. In this case, you still don't know for sure if thermoswitch is good or bad. So best to remove it and test its resistance in pot of water at room-temperature. Then test it again as you bring pot to boil. If when water boils and thermoswitch still hasn't closed circuit (zero-ohms between terminals), then you can 100% confirm that it's bad.

Not sure what those wires are, probably not related to fan in any way. Can't find any brown & green wires near front of bike in any wiring-diagrams. Probably coincidental that your fan stopped working. Trace where those wires go at other end.

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Old October 16th, 2019, 08:55 AM   #10
Zolland
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Forgot to mention, I did test wires on the fuse box but may have tested the wrong ones. Are these the wires you were talking about? If so I tested the one on the left and confirmed +12, but just noticed the one on the right in the picture so need to do that later tonight.

Fuse Box

Sorry, I'll try to clarify. I did originally bridge with a paper clip, but it didn't work. So I used a live wire (that used to be going to the grip heaters, but had to cut) and connected it directly into the other side of the thermo switch sensor connector as shown in the picture.

Also I'm not low on coolant just worried it isn't circulating. I'll try to test with boiling water next week, but I don't think I'll have time to do that tonight or over the weekend

Edit: Just noticed the image above for the visual is broken, fixing it now
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Old October 16th, 2019, 10:33 AM   #11
DannoXYZ
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Hmm, interesting. I only see one white/blue wire on diagram. Others are white/green and white/black. There is blue/white wire that goes to headlamp. That might be 2nd-wire on right.



Test for voltage on these:

- fuse box white wire, should have +12v full-time regardless of ignition-switch
- fuse box white/blue wire, should have +12v full-time
- fuse box white/black wire, should have +12v full-time
- white/blue wire at thermoswitch connector, still not sure about this one.

Last futzed with by DannoXYZ; October 16th, 2019 at 07:09 PM.
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