Fan pulsing when bike is off - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 8 (permalink) Old 04-24-2011, 02:45 AM Thread Starter
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Fan pulsing when bike is off

Greetings, this is my first post as i found the forum searching for an answer to this. I did perform a few searches here and didn't find anything.

I recently got a 94 vulcan 750, I've put a couple hundred miles on the bike and all has been good.

i came home to tonight and the fan behind the radiator was pulsing on and off. The bike had not been running for around 12 hours.

I started the bike up, let it warm up some and cut it off, it was still doing the same thing.

Right now I have the fan disconnected to not drain my battery.
any ideas what is causing this?
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post #2 of 8 (permalink) Old 04-24-2011, 03:04 AM
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There is a switch on the lower corner of the radiator that turns the fan on when it gets hot. I don't recall which side it's on, but it has a single wire going to it. That switch could be bad, or the contacts could be corroded.
Plug your fan back in, and unplug that wire to the sensor, and see if the fan shuts off.
If it does, then you have a bad sensor. If the fan keeps running, then I'm not sure what it could be. Check all of your ground wires on the frame, and engine.
Someone will chime in here and be able to give you some more help on this.
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post #3 of 8 (permalink) Old 04-24-2011, 06:53 PM Thread Starter
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i messed around with it some today, with the fan disconnected I can actually hear a buzzing in the junction/fuse box that matches the pattern the fan was pulsing in.

It stops when I remove the 30v fuse, which of course cuts power to the lights/starter/fans etc.

Dunno if that gives anyone that may know the issue any help or not.


Eta: I did try disconnecting the sensor, it continued to happen so I don't think its that.

Is it possible to replace the fan relay itself on these bikes or is it a full junction box replacement? i can't seem to find the actual relay

Last edited by Followthehollow; 04-24-2011 at 08:35 PM.
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post #4 of 8 (permalink) Old 04-25-2011, 12:07 AM
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Quote:
Originally Posted by Followthehollow View Post
i messed around with it some today, with the fan disconnected I can actually hear a buzzing in the junction/fuse box that matches the pattern the fan was pulsing in.

It stops when I remove the 30v fuse, which of course cuts power to the lights/starter/fans etc.

Dunno if that gives anyone that may know the issue any help or not.


Eta: I did try disconnecting the sensor, it continued to happen so I don't think its that.

Is it possible to replace the fan relay itself on these bikes or is it a full junction box replacement? i can't seem to find the actual relay
The JB is not designed to be repaired, just replaced.
I`m not sure exactly what all the relays are inside the JB.

However somebody posted pictures a few weeks ago of an opened up JB, exposing the relays inside.
I believe at least one member bypassed the headlight relay in the JB and uses a toggle switch to turn them on.
So if there is a fan relay in the JB,you may be able to replace it, or install a switch. Not ideal maybe, but possible.

Someone with more electrical savvy than me will have to guide you from here.

Gordon

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post #5 of 8 (permalink) Old 04-25-2011, 12:26 AM
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Quote:
Originally Posted by Followthehollow View Post
i messed around with it some today, with the fan disconnected I can actually hear a buzzing in the junction/fuse box that matches the pattern the fan was pulsing in.

It stops when I remove the 30v fuse, which of course cuts power to the lights/starter/fans etc.

Dunno if that gives anyone that may know the issue any help or not.


Eta: I did try disconnecting the sensor, it continued to happen so I don't think its that.

Is it possible to replace the fan relay itself on these bikes or is it a full junction box replacement? i can't seem to find the actual relay
you can get an auto motive relay and by pass the one in the JB ,I did this to mine as the fan relay did not work at all.
Use the radiator sensor to provide the ground for the coil in the relay and use the contacts in the relay to connect battery positive to the fan,run the other lead to ground from the fan motor. I used the accesory leads inside the headlight bucket to pick up the power for the relay and mounted it all under the leftside neck cover ,and it worked great and was on a fused circuit.

My relay was stuck open inside the Jb ,yours seems to be shorting to ground and trying to energize the relay,you need to find out which wire provides power to the relay coil in the JB and unhook it if you go this route ,because it sounds like the coil would still be trying to energize and may drain the battery.

Some one on her had a JB for sale for around thirty bucks the other day,that may be your best option.




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post #6 of 8 (permalink) Old 04-25-2011, 02:26 PM Thread Starter
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Is the junction box one of the parts that is universal between all the 84-06 vulcan 700/750s?

I'm going to take mine out tonight, take it apart, look it over, and spray the crap out of it with contact cleaner.

If that doesn't work I'll just order a new one I guess, wanted to make sure any of those will fit.
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post #7 of 8 (permalink) Old 04-25-2011, 11:27 PM
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Mine will do the same thing from time to time if the bike is really hot as soon as I turn off the bike the fan will kick on for a minute or so and shut itself off.

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post #8 of 8 (permalink) Old 04-26-2011, 12:33 AM Thread Starter
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Got it fixed at least for now.

After browsing the verses, i determind the easiest solution to attempt was the same one that works for many older electronics.

I smacked the junction box with a wrench and I guess it tripped the relay back.

Started the bike up, let it heat up a while. The fan kicked on as normal, Imthen killed the bike and the fan ran for about another minute and cut off as it should.

No more pulsing/clicking

The bike had sat all winter before I bought it so must just be a sticky relay
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