Electrical Help-KTM 530 xcw

[Hank]

Everything you never wanted to know about cooling fan switches!

https://www.youtube.com/watch?v=fQWQQr9EWMk

[Hank]

My switch is open at ambient temp,
Like I thought it should be.

[Robmicgrn]

I just got home and checked mine. Same settings,same reading.

[Bogus Jim]

I think I would also check resistance between each of the terminals and ground, just to make sure one of the terminals in the switch is not conducting to ground.

[Hank]

+1 almost seems like that has to be the case if disconnecting nothing but those leads caused the current to drop.

Sent from the Altair 8800 I carry around.

[Hank]

Both terminals to ground are open on mine.

Sent from the Altair 8800 I carry around.

[Robmicgrn]

I think I would also check resistance between each of the terminals and ground, just to make sure one of the terminals in the switch is not conducting to ground.

You lost me on that one. The terminals on the thermo switch or the terminal wires going to the switch....

[Hank]

Check the resistance  from each terminal on the switch to the radiator itself.  Both should be open.

Sent from the Altair 8800 I carry around.

[Robmicgrn]

Got it. As soon as I get out of the office I will get home and take a look!

[Robmicgrn]

Same readings as before. Switch is not shorting out to ground. One of the wires going to the switch, did, as I believe it should. Now what??? 

[Hank]

Hmm.. well one wire should have a path to ground, the one that goes to the fan, so I think that's normal.   The other goes to the battery positive terminal.

Think of this circuit as a light bulb and a switch.    Power goes to the switch, when the switch is closed, power flows to the light (fan in this case) and to ground.  Its really a simple circuit.  I'll look at my service manual wiring diagram and make sure I'm not over simplifying something.

It seems really really odd to me that you had a current drop in your first test when you disconnected only the fan switch leads, if the switch terminals are not conducting to ground.   I can't think of why that would be..   but, I'm no genius at this stuff either

I might be out of ideas?

[Hank]

Yeah looked at the diagram.... its as simple as that.. battery +(Yellow /red wire in the harness) to the switch to the fan.    So I think your problem lies elsewhere, but I'm still confused why your measured current dropped when you disconnected the wires from the switch.

[Hank]

The way this system works is a little weird, and I don't think I understand it totally, but I'm getting there.

The bikes don't have a regulator / rectifier, just a regulator.  The stator is a "split" design that puts out both AC and DC, and the way it looks to me the regulator regulates both the AC and the DC.    The AC runs all the lights, the regulated DC is used to charge the battery, so as I understand the only things that are connected right to the battery are the fan, the starter relay and start button, and the regulator.

You can see that the fan runs directly off the battery by touching the two fan switch wires together, the fan runs whether the bike is running or not.

I guess I'd suspect the regulator next.

I'm going to print out the wiring diagram and make some notes to make it easier to follow.. KTM's wiring diagrams aren't the clearest things I've ever seen.

None of this is probably real helpful

[Hank]

The internet is sure full of half information.

But I think I have it figured out now.    The Stator only puts out AC (makes more sense) and what KTM calls a regulator is indeed a regulator / rectifier.

Not that that changes anything for what you are trying to figure out.. I still suspect your regulator/rectifier could be the problem since it seems we've eliminated the fan switch... although your earlier test results still don't add up.

Drawing directly from the battery:
Fan
Starter button
Starter relay
(the above are either ON or OFF.. should be no leakage and it seems we've eliminated that possibility with the fan switch)
The R/R
The speedo.

That's it, the CDI and lights etc are all powered by AC and isolated from the battery.   I'm gonna have to get my meter out and verify some of this stuff.

[Lonesome Dave]

I think; once the stator produces the AC, the R/R changes it to DC.  It then controls the voltage depending on draw and rpm for charging and running of the different circuits.  I don't believe you have both AC and DC running around the machine.  Just AC converted to DC and then regulated.  I think likely the CDI is probably it.  I have no idea how to test it.  Other than a charged battery, disconnect the cdi and wait, or maybe measure the current draw as previously with the cid unhooked.