No charging though everything tests great (and has been replaced) - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Electrical
Where does this wire go?
Includes Electrical mods, Lights, Stator,
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post #1 of 74 (permalink) Old 09-19-2015, 11:52 PM Thread Starter
1986 VN750
 
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No charging though everything tests great (and has been replaced)

I'm about to rip out my wiring harness and replace it. This is getting crazy.

I get barely any charging right now, yet every individual piece tests fine, or better than fine.

Replaced
  • JB (I had a spare)
  • MOSFET R/R (I also had a spare)
  • TPE Stator (just in case, plus I can re-use the other one in my second VN)
  • Battery (last ditch effort since everything else was fine.)

Tests:
  • MOSFET R/R - tests fine. Puts out 15v when unplugged from the bikes electrics.
  • TPE Stator - 20-60vac all legs, zero continuity to ground.
  • Headlight Relay Bypass (no change)

The bike gets 12.5-13.3v, never more. Barely increases with RPM, though stator is definitely pushing out vac. I was getting as low as 9v @ the ignition coils with the fan running, so I did the ignition coil mod. Now I get battery voltage at coils (runs better now, no longer dies when the fan kicks on due to low voltage).

MOSFET bypasses stock wiring harness (direct to battery, 30a inline fuse). Replaced the switching style inline fuse with a standard type, no change.

I am thinking there has to be some sort of short somewhere causing this issue. I can't think of any other reason why my voltage would be so low. I have 2 spare harnesses, so I guess it may be prudent to swap it out as I can not see anything that would cause this.

Any thoughts? Am I missing something stupid? I mean I've seen 100s of VNs diagnosed here and I swear I've covered all the bases.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #2 of 74 (permalink) Old 09-20-2015, 01:45 AM Thread Starter
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Is the headlight relay sense wire supposed to have any continuity to ground? It does, no matter what JB.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
thtanner is offline  
post #3 of 74 (permalink) Old 09-20-2015, 03:25 AM
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Have you tried moving the harness while
Testing everything? I had a burned wire that was arching out but only every so often. Everything tested fine on my bike as well.

2007 Kawi ninja-sold
1990 Vulcan 750-sold
2001 Honda Sabre 1100-wrecked then sold
2013 Victory Highball
Ride on wolf
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post #4 of 74 (permalink) Old 09-20-2015, 07:48 AM
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as mentioned, look for a short (or otherwise a very high electrical load of not a direct short).

if the RR is putting out good voltage level with minimal load (un hooked), put the output drops when hooked up, either a very heavy load exists which is pulling down the voltage by 'overloading' the charging system, or their is a bad connection or failing RR.

the heavy load will cause voltage drop due to the amount of current (amps) avail from the stator being insufficient for the regulator to keep the output voltage up.

bad connection will cause the voltage at the battery to be less than what the RR is thinking the battery has (voltage drop across the wiring/connections).

try checking the voltage right at the RR when connected if possible (many multimeters have leads with sharp enough points to be able to pierce insulation for this type of measurement).

also, ground connections can affect the output voltage when under load, so don't look just at the positive side of the system.

the headlight relay does appear to be grounded thru the starter solenoid. the trigger wire from stator has a diode in it, but does end up grounding thru the solenoid.

2005 VN750

Sold 11-27-17
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post #5 of 74 (permalink) Old 09-20-2015, 08:52 AM
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My system gained 1v when I bypassed the start circuit from the JB. Seems to be a common fault in the JB, and a possible source of stator failures. Ever have any trouble with the start button? I also have the headlight relay bypass in use.

I could try to dig up the post if you're interested, you can test it before cutting any wires. MTB has done the same bypass. Before the bypass, the new system topped out at 13.5 and would brown out to 12.5 or so, it's a solid 14.5 now except when the fan is running.

20v AC seems a bit low, did that leg happen to be on the headlight relay? I'd bypass the start circuit and headlight relay if so.

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

Last edited by Spockster; 09-20-2015 at 08:56 AM.
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post #6 of 74 (permalink) Old 09-20-2015, 12:35 PM Thread Starter
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Quote:
Originally Posted by Spockster View Post
20v AC seems a bit low, did that leg happen to be on the headlight relay? I'd bypass the start circuit and headlight relay if so.
Stator was disconnected from wiring harness (and headlight relay). All legs produced the same voltage (20vac 1k rpm, 60vac+ at 5k rpm).

Quote:
Originally Posted by michiganteddybear View Post
try checking the voltage right at the RR when connected if possible (many multimeters have leads with sharp enough points to be able to pierce insulation for this type of measurement).

also, ground connections can affect the output voltage when under load, so don't look just at the positive side of the system.
The R/R bypasses the stock wiring harness. Voltage is the same @ the r/r connector as the terminals on the battery when connected.

I did triple check grounds, just in case. No dice there either.

I have also jiggled wiring with no success, but it's tight against the frame in places and that's where i'm imaging the issue lies..

I'm really leaning towards a short as there isn't much else that can put that kind of load without being a major issue. I'll probably just pop the tank off in an hour or two, put in a spare harness, and go from there.

Who knew a 30 year old bike would have wiring gremlins.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #7 of 74 (permalink) Old 09-20-2015, 12:43 PM
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Ok, sounds like stator output is ok.

The short .... could still be that circuit in the JB, even both the JBs you tried.

If you wanted to try the bypass as a test, you could simply pull the correct wires from the 10-pin plug on the JB, tie them together and start the bike. Then check the charge voltage.

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 #8 of 74 (permalink) Old 09-20-2015, 12:47 PM Thread Starter
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Quote:
Originally Posted by Spockster View Post
Ok, sounds like stator output is ok.

The short .... could still be that circuit in the JB, even both the JBs you tried.

If you wanted to try the bypass as a test, you could simply pull the correct wires from the 10-pin plug on the JB, tie them together and start the bike. Then check the charge voltage.
At this point, it can't hurt to try. It'd be crazy if two JBs were bad, but definitely not impossible. I do have a third to try, too. (I've been stockpiling, I had two VNs here - about to start on the second was just trying to 'finish' this one)

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
thtanner is offline  
post #9 of 74 (permalink) Old 09-20-2015, 01:01 PM
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We see a lot of wonky JBs here. Searching for my thread on the bypass, there are a lot of posts about this start button problem and dead shorts in JB. I've seen enough to think this is a significant bypass to do, even as a preventative measure.

Link to the thread where I fixed mine:
https://www.vn750.com/forum/19-electr...wont-work.html

The bypass:

Quote:
The Fix: Clipped two wires off the 10-pin JB plug: black/ red and yellow/red, spliced these two together.
Note: This bypass also disables the nanny switches on the sidestand and clutch.

I think there's just too much BS occurring in the JB.

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 #10 of 74 (permalink) Old 09-20-2015, 01:31 PM Thread Starter
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I'm throwing in a new harness in a minute, and if problem persists, I will then try that mod. I don't mind the safety switches, but if that's the issue then I'm more than happy to disable them

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
thtanner is offline  
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