Bad run switch/start button? No ground? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 04-09-2015, 10:06 PM Thread Starter
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Bad run switch/start button? No ground?

I'm near the end of my rebuild and I've put the wiring harness in, went to turn the engine over (no fuel, but wanted to make sure it did) and nothing. I've gone back and forth and done some testing. I've narrowed the issue down to the run switch and/or start button. I think the issue is limited to the start button, but I'm not sure.

First, I unplugged the whole start/run assembly from the main harness. Then, I shorted the two pins that the run switch appears to be wired into (red and yellow/red) and then shorted the black/red wire to the frame ground. The starter turned over!

I left the run switch wires jumped and plugged the harness back in and tried the start button, but nothing. Took apart the run switch and start button, checked the connections and cleaned all the contacts with a Dremel with a wire brush attachment - put it all back together and nothing.

I'm at a loss at the moment, any ideas? I should note I replaced my handlebars with new ones which are painted black, and also painted the handlebar clamp black - I checked with a multimeter and the handlebars are not showing up as ground. Do I need to scrape away some paint so the handlebars are considered ground?

'92 Kawasaki Vulcan 750

Mods:
Rattle-can high gloss black paint job
Frame, engine, Headers/exhaust painted satin black
Ears shaved, K&N pod filters
TPE Stator, MOSFET R/R, Magna Power AGM battery
Pickup Coil mod
New mirrors, grips, cables
VN900 seat
Straight pipes with 8" baffles
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post #2 of 17 (permalink) Old 04-09-2015, 10:39 PM
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I'm not clear about how you did the tests, but I just had to work on a start button problem here: https://www.vn750.com/forum/showthread.php?t=69625 There's a wiring diagram in that thread.

When it's all hooked up, there should be 12v on both sides of the kill switch with the key on and kill sw. in run position.. The red wire on the kill switch hops over to the start button, so it should have 12v at the start button too.

The black/red from the start button, runs to the red plug behind the front ignition coil, then on back to the junction box. There should be 12v on this wire when the start button is pushed. Check at the start button, the red plug, and lower plug on the junction box.

If you have 12v all those places and you don't hear the relay click in the junction box, you most likely need the same fix in the link above.

The paint is ok, since none of those switches ground on the bars.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
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post #3 of 17 (permalink) Old 04-14-2015, 10:44 PM Thread Starter
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I tried the fix in the other thread and while it does seem to work (start button works), I'm getting some odd symptoms that make me think something worse is wrong. The cooling fan is on now at a low speed all the time when the key is in the On position. Additionally, if I push the starter once and let go, then try it a second time it no longer does anything. Finally, if I try something else like the horn, the horn barely works (and it worked fine before) but when I hold the horn button down the fan seems to speed up to full speed.

If I unplug the fan connector, the start button no longer works. WTF?

'92 Kawasaki Vulcan 750

Mods:
Rattle-can high gloss black paint job
Frame, engine, Headers/exhaust painted satin black
Ears shaved, K&N pod filters
TPE Stator, MOSFET R/R, Magna Power AGM battery
Pickup Coil mod
New mirrors, grips, cables
VN900 seat
Straight pipes with 8" baffles
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post #4 of 17 (permalink) Old 04-14-2015, 11:34 PM
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Check all your grounds.these are finicky electrical systems

ONE RATS ASS GIVEN PER POST
Support your local FREEBIRDS MC
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I am a BIKER and i'm proud.FREEBIRDS MC CENTRAL NY

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post #5 of 17 (permalink) Old 04-14-2015, 11:41 PM
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Starting to sound like a Junction Box meltdown. Replacing the JB with another or getting KC to fix yours. The JB isn't really serviceable, but a couple of people have it figured out.

The battery voltage is up to par? At least 12.5v?

Grounds all tested good? The fan operates off ground, if you ground the wire on the fan switch, the fan should run. (just mentioning that to show the fan runs off ground)

Still thinking the JB is toast, but I'll think about this more, right after I get my taxes done. Sorry I can't be more help at the moment, things are hectic around here right now.

Maybe someone else can add some ideas.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #6 of 17 (permalink) Old 04-15-2015, 01:16 PM Thread Starter
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I checked my grounds a few days ago and think I'm good there, was worried because I painted the frame and did have a grounding issue at first - I think. I took my dremel with a wire brush attachment and removed all the paint from the grounding points:

1. Battery negative to frame
2. Engine grounding cable to one of the screws that hold the battery box to the frame.

I'm thinking the same with the JB, I just find it so frustrating that it worked just fine before I tore the bike apart and now it's suddenly broken.

'92 Kawasaki Vulcan 750

Mods:
Rattle-can high gloss black paint job
Frame, engine, Headers/exhaust painted satin black
Ears shaved, K&N pod filters
TPE Stator, MOSFET R/R, Magna Power AGM battery
Pickup Coil mod
New mirrors, grips, cables
VN900 seat
Straight pipes with 8" baffles
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post #7 of 17 (permalink) Old 04-16-2015, 04:59 PM
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1. Battery negative to frame
2. Engine grounding cable to one of the screws that hold the battery box to the frame.

3. the battery box to the engine

Check that the battery box, frame, and engine are all grounded by checking continuity from battery ground to everywhere else on the bike.
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post #8 of 17 (permalink) Old 04-16-2015, 05:58 PM
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Check your ignition switch too, had very similar situation after putting everything back together on mine, lights came on, horn worked etc, but it just wouldn't turn over, pulled the starter solenoid and that was good. Finally I decided to heed the advice given early that I figured it couldn't be because my lights and everything else worked. I took the ignition switch apart and cleaned all the tracks with rubbing alcohol and put it back together and it worked like a dream. Now I have to do it again because it is only working when i push it all the way to park and slowly pop it back to on, but I know what I need to do now!
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post #9 of 17 (permalink) Old 04-17-2015, 06:03 PM Thread Starter
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Checked all grounds last night, everything looks good and no issues there. Also took some time and properly wired in the R/R I bought last year with clips and new wires. Unfortunately, a new junction box won't be here until next Thursday... is there anything else I can try in the mean time to ensure the JB is the problem?

'92 Kawasaki Vulcan 750

Mods:
Rattle-can high gloss black paint job
Frame, engine, Headers/exhaust painted satin black
Ears shaved, K&N pod filters
TPE Stator, MOSFET R/R, Magna Power AGM battery
Pickup Coil mod
New mirrors, grips, cables
VN900 seat
Straight pipes with 8" baffles
kagaku is offline  
post #10 of 17 (permalink) Old 04-17-2015, 06:23 PM
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All I can add is ... Had a problem with the fan not kicking on, turned out to be a loose spade in the JB plug. I ended up pulling all the spades out of the plug and pinching them a bit so they fit tighter.

I found it by wiggling the wires at the plug while having the fan switch wire grounded. When I hit the wire, the fan came on. So turn your key on and wiggle some wires, see if it straightens up.

If you do this ... Use a needle to press the tab on each spade, that will release it from the plug. Pay attention to which hole it comes from, some holes are empty. The hole is T-shaped, the tab is on the bottom leg of the T.

Could try the search, I know slimvulcanrider did a lot of work on JBs in the past.

The way your fan was running, I would guess something in the JB is grounding when it shouldn't. Or, the JB could be sending power to the fan regardless of the fan switch operation. But I can be wrong too.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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