Fan switch question - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 4 (permalink) Old 09-02-2016, 07:59 PM Thread Starter
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Fan switch question

Hey guys sorting out some gremlins over here. My fan switch has never worked on my bike since I bought it. (sp2) So I ran a manual switch and thats been fine. However I just rewired the whole bike and fixed a few other electrical issues and I believe fixed the fan temp switch issue. My question is as follows. Is there a way I can test to see if it's going to kick on when it gets warm without getting it warm?

I ask because it's apart right now and if I need to re run a manual switch now would be a good time, as opposed to assembling and de-assembling again lol... I'd prefer it operated automatically as designed though. I don't think there is a way but I learn something new everyday.

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post #2 of 4 (permalink) Old 09-02-2016, 08:21 PM
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How far apart? I believe the SP2's use a thermosensor, not a switch. That sensor will give the ECU the signal it need to operate the fans. They should kick on at 219F and off at 209F, or close to that.
Number 13.

That said, I wouldn't just go buy one with out eliminating the other possible problems. Consult your svc manual.

Good luck, must be a pain having to constantly monitor engine temp.
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post #3 of 4 (permalink) Old 09-02-2016, 08:51 PM
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I am after all just a knuckle dragger but couldn't you just remove the temperature bulb/sensor from the radiator (I'm assuming there is only one) and with it still connected to the wiring harness place it boiling water somehow. If you were to just check for resistance changes at the temp bulb terminals that would only validate the bulb not the entire system.
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post #4 of 4 (permalink) Old 09-02-2016, 09:01 PM
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I don't know of a way to get it working without getting it up to temp. Could use a multi meter to check the circuit. As long as no shorts in system, and ect is sending right temp signal to ecu, then if should work. I would start by running am ohm resistance check on circuit. Set your multimeter to ohm and the 200 setting. Then touch one lead to the black wire on fan relay, and other lead to the right fan switch connector and see if have a low resistance reading, should be around .8 that will show if you have a good circuit. If don't you will have to start working your way backwards testing the circuit. Right fan switch to left fan switch, if that's good, then left fan switch to blue connector where front and rear harness plugs in. If have good circuit from left fan switch to front part of blue connector, then go from back half of blue connector (which is rear harness) to fan relay in tail. If don't have any shorts or breaks in any wires, then can remove ect and test it according to manual. That's what I had to do, ended up having a bunch of broken wires in rear harness.
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