Troubleshooting a Fan That Won't Come on - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 12 (permalink) Old 07-09-2008, 10:10 PM Thread Starter
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Talking Troubleshooting a Fan That Won't Come on

I tried to run a search on this the last couple of evenings, and am coming up with useful threads, but not all the info in one spot that I was looking for. If this is redundant, my apologies and, DMAG, just kill this thread. If it's helpful for anyone, though, here goes:

Ok, so you're riding, it's hot, your temp gauge is climbing at the stop light and you don't hear that lovely "Whrrrrrrr" of your fan. What's going on? And how do I find out where the problem is?

There are basically four areas where your fan can go kerplooey: at the fan switch (the little copper-colored nub that sits off the bottom of your radiator); at the fan motor (black, two-prong connector that links into your wiring harness on the left side of the bike); the relay (in the junction box); or there's something amiss in your wiring. The Haynes manual (page 3-4)offers a pretty clear description of how to troubleshoot, so here you go:

1 If the cooling fan isn't coming on, first check the fuses. If the fuse is blown, check the fan circuit for a short to ground. If the fuses are all good, however, disconnect the fan electrical connector (the two-pin deal). Using two jumper wires, apply battery voltage to the terminals in the fan motor side of the electrical connector (that is, don't hook up the jumpers to the wiring harness). If the fan doesn't work, you've got a bad motor and need to replace that.

2. If the fan does come on in step 1, the problem lies in one of the three other areas (switch, jbox, or wiring). Remove the electrical connector from the test area in step one, hook that connector back together, and proceed to step 3.

3. The Vulcan 700/750 has a single-wire switch harness. Disconnect the electrical connector (flat black connector, BK/Y wire) from the fan switch (again, copper-colored deal on the lower left of the radiator). Attach a jumper wire to the harness side of the connector and ground the other end of the jumper wire to the frame. If the fan comes on, the circuit to the motor is fine, but the thermostatic fan switch is defective. You will need to replace the switch, or do a temporary work-around, as described further below.

4. If the fan still doesn't come on, trace the fan relay (in the junction box) - use the wire colors for identification and place your hand on it. Repeatedly touch the jumper wire to ground as detailed in step 3 above. If you feel and hear a clicking sound inside the relay, the relay is good and the fault must lie with the wiring. If no clicking is heard, your relay is faulty and must be replaced. Some Forum folks have been able to tear into the Jbox and replace the relay, but Haynes and others recommend replacing the junction box altogether.

Seems like lots of folks have bad fan switches at the moment, and rumor has it that they're expensive. A temporary work-around (thanks, liljd for the inspiration) is to hook up a toggle switch that allows you to control when the fan comes on. Attached the ground wire that would go to the switch to one lead on the toggle switch; affix another wire to the other lead on the toggle and ground this one. You can use those quick connectors (more color-coded ones!) to create this link up. Attached the toggle switch to someplace easy to reach on the frame, and you're good to go until you can afford a new fan switch. Just remember to turn it off after about 30 seconds - run it too long or you forget about it, and you'll have a burned out motor and a dead battery (probably in that order). Here are some pics of the toggle switch I hooked up this evening: Black ground lead from wiring harness is to the left; the bright yellow lead coming off the right is the ground connection to the frame; and the switch is affixed to the inside (lateral) of the engine guard via two zipties.

Hope this helps someone. And, again, if this is redundant info, just ignore me.

C

Last edited by Crobins365; 10-05-2008 at 07:50 PM.
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post #2 of 12 (permalink) Old 07-10-2008, 01:14 AM
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Great write up!

Chris
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post #3 of 12 (permalink) Old 07-10-2008, 08:15 AM
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I used the hot lead for the toggle. Safer IMO for the wiring. and you can even use a toggle with a light in it to see if it's on or not. I have no pics of mine but I placed my toggle on the handle bars for easy reach.

Your welcome and thanks for writing up this wonderful Tech sheet!!!!!

James
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Last edited by liljd; 07-10-2008 at 08:18 AM.
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post #4 of 12 (permalink) Old 07-10-2008, 08:31 AM Thread Starter
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Quote:
Originally Posted by liljd View Post
I used the hot lead for the toggle. Safer IMO for the wiring. and you can even use a toggle with a light in it to see if it's on or not. I have no pics of mine but I placed my toggle on the handle bars for easy reach.

Your welcome and thanks for writing up this wonderful Tech sheet!!!!!
Was your fan out or the switch? If the latter, can you just provide a little more info as to why the hot lead would be the safer option? (Sorry, the above write-up hit the limits of my electrical capacity...).

C
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post #5 of 12 (permalink) Old 07-10-2008, 10:42 AM
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Quote:
Originally Posted by Crobins365 View Post
Was your fan out or the switch? If the latter, can you just provide a little more info as to why the hot lead would be the safer option? (Sorry, the above write-up hit the limits of my electrical capacity...).
It is my relay thats bad on mine. If you leave a hot connection on at all times but with out a ground you can burn something up. Basicly the fan has power at all times that way.

When you use a hot lead for the toggle you can just shut off the power to the fan at any given time. It's just safer to keep the ground connected and not the hot. The troggles are made to cut a hot lead and not the ground as universal rules for consistancy.

Also if you make ground by mistake it will turn on the fan and run down the battery and such. So it's better to use the toggle to cut the hot and not the ground. You can use the ground but accidents can happen quicker that way.

Also try to water proof the toggle in some way so water won't get in and corrode or turn on the fan.

James
1985 vn700 (T'Plana)
Gremlin bell
HD-O shield
saddlebagged
custom made supports
tool bag
extended backrest
Protac backrest
Highway pegs
custom mirrors
custom grips
V&H cruisers
lever covers
DieHard AGM
Kuryakin battery gauge
and LED taillights
marbled

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Last edited by liljd; 07-10-2008 at 10:45 AM.
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post #6 of 12 (permalink) Old 07-10-2008, 10:56 AM Thread Starter
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[QUOTE=liljd;62765] You can use the ground but accidents can happen quicker that way.
[QUOTE]

What kind of "accidents"? Battery run-downs and burned out motors, or something worse??

C
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post #7 of 12 (permalink) Old 07-10-2008, 11:02 AM
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[QUOTE=Crobins365;62766][QUOTE=liljd;62765] You can use the ground but accidents can happen quicker that way.
Quote:

What kind of "accidents"? Battery run-downs and burned out motors, or something worse??
Basicly.....

you just don't want power going to it at all times cause it can ground out then it's on and you'll never know it.

That and if anyone ever dives into it later on due to you taking it to a mech or someone buys it from you it can confuse them.

Oh and if you cut the power lead you prevent unknown surges from hitting the fan motor or worst...the stator or R/R themselves.

James
1985 vn700 (T'Plana)
Gremlin bell
HD-O shield
saddlebagged
custom made supports
tool bag
extended backrest
Protac backrest
Highway pegs
custom mirrors
custom grips
V&H cruisers
lever covers
DieHard AGM
Kuryakin battery gauge
and LED taillights
marbled

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Tn VROC #134

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Last edited by liljd; 07-10-2008 at 11:06 AM.
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post #8 of 12 (permalink) Old 07-10-2008, 11:53 AM Thread Starter
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Shoot - and here I was so proud.

I'll rewire this evening. Gotta do it right!

C
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post #9 of 12 (permalink) Old 07-10-2008, 12:01 PM
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Quote:
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Shoot - and here I was so proud.

I'll rewire this evening. Gotta do it right!
I think you did an excelent job!!!!! Were all allowed a mistake or two right???

James
1985 vn700 (T'Plana)
Gremlin bell
HD-O shield
saddlebagged
custom made supports
tool bag
extended backrest
Protac backrest
Highway pegs
custom mirrors
custom grips
V&H cruisers
lever covers
DieHard AGM
Kuryakin battery gauge
and LED taillights
marbled

____________________

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Tn VROC #134

www.youtube.com/thetrueliljd
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post #10 of 12 (permalink) Old 07-26-2008, 11:57 PM
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cool , i put a hole in the plastic just infront of the gas tank and put my switch there . i don't plan on getting a new fan switch ( $72.) , i like to be able to shut my fan off before i stop for gas .
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