Charging System Issues - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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Where does this wire go?
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post #1 of 61 (permalink) Old 07-15-2012, 05:15 PM Thread Starter
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Charging System Issues

FINAL UPDATE (11/27/12)
The saga has ended at last. If you want to see what the problem was and how it was solved, jump directly to Post #59 in this thread. Many thanks to all who participated in this thread especially Slimvulcanrider.

Gvaughn111
END OF UPDATE

IMPORTANT UPDATE (7/18/12)
To anyone who has participated in this thread (or wishes to do so), please go directly to Post #23 and read it thoroughly before posting your Reply. If, after reading that Post, you think you need more information, then go ahead and read as much of the thread as you want to. You will probably find what you need in it. Thank you all.

GVAUGHN111
END OF UPDATE

CORRECTION: Read this first

By the way, I did find a flaw in my most recent testing. I thought I had good readings from the RR ground to the battery negative post and from the RR hot lead to the positive battery post. I was in error. From the RR ground to the post, I get .6V and from the hot lead to the post I get a highly variable reading between .15 and .3V. ElectroSport's flowchart indicates both readings should be no higher than .2V. So it would seem I do have a bad connection, probably on the ground side, but I was unable to locate any such connection the first time I went through the wiring harness. I did get some seemingly bad resistance readings, but eventually they went away and it seemed I had good continuity and good charging voltage at the battery post (14V or greater) before I put everything back together the first time. Can anyone tell me the best way to check for a bad connection? Nothing seems fused; loose; arced or corroded.

END OF CORRECTION
I bought a used 1990 Vulcan 750 recently. There is a problem in the electrical system that seems to appear as a charging problem. There is much helpful information on the forum which I have already reviewed and tried to apply, but it seems as if I am just running around in circles. Perhaps someone can get me pointed in the right direction when I describe my symptoms.

Voltages off the stator seem good. I get in excess of 70 volts on all three yellow wires at 4000rpm. I have a new RR since I first suspected that was the culprit. I also have a brand new battery since I suspected it next. I did the ElectroSport flowchart tests that suggested a bad connection on the ground side of the RR output. I explored that possibility by unbinding the harness and checking for bad connections through the wiring and back to the battery. I did not find any obviously bad connections, but apparently I did something to eliminate the bad connection because after rebundling the harness, the bad voltage reading disappeared, and I had good charging voltage at the battery terminals (13.5V at idle 14+ at higher Rpms). I breathed a sigh of relief and thought my problems were over.

Next morning I tried to start the bike. Battery was almost completely dead! (It had been fully charged the day before.) Jumped the bike and got good charging voltage but did not ride. I took the battery out and put it on trickle charge overnight. I installed the battery after full charge. Started the bike and it fired right up. I then stopped the engine and disconnected the battery and let it sit overnight. This was just an attempt to rule out a bad battery. The next morning I reconnected the battery and the bike started fine.

Before starting, I did put my DMM in line with the battery at the battery negative post to check for any current leakage. None was detected. With the bike running, the charging voltage at the battery posts is now less than 13V even at high rpms. Stator voltages are still good. There is no indication of the old fault on the ground side of the RR. However, with the bike at idle, I pulled the connector at the RR off. When I did this, the rpms ramped up by about 400-500 rpms. I stopped the bike and walked away for about 30-45 minutes. When I came back to start the bike again and explore further, the battery was dead! No, I did not leave the ignition switch on!

I am not an electrician or a mechanic, but I do have some limited skills in both areas. I cannot imagine what would drain the battery so quickly, and I do not know if the jump in rmps with the removal of the RR connector is normal.

Can anyone suggest a reasonable manner in which to proceed with the symptoms I have described? Is this likely a junction box issue or some other issue independent of the charging system? The battery won't be fully charged now until tomorrow, at which point I would like to see if I can track down the problem or problems. Any guidance would be GREATLY appreciated. Thanks.

Last edited by gvaughn111; 11-26-2012 at 03:38 PM.
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post #2 of 61 (permalink) Old 07-15-2012, 05:37 PM
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Quote:
I am not an electrician or a mechanic, but I do have some limited skills in both areas. I cannot imagine what would drain the battery so quickly, and I do not know if the jump in rmps with the removal of the RR connector is normal.
I think you did very well for your experience.

Quote:
Before starting, I did put my DMM in line with the battery at the battery negative post to check for any current leakage. None was detected.
I would have performed this on the + side of battery also (not believing none measured).

At this point I too would be asking for another('s) brain thought on this.

Q: Are you sure the R/R has a great ground ? Was it mounted ? Place a jumper lead from R/R to negative battery terminal, then measure again. Three issues are at hand here & that would be my next effort.
Give it a shot...I'll be on here the rest of today/evening.

Possible Junction Box issues ???????


WilliamTech

'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
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Splines Lubed - 11/4/2012 - MF AGM Battery
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Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
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post #3 of 61 (permalink) Old 07-15-2012, 05:38 PM
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i had charging problem, i found the 6 pin connector at the volt reg was cracked inside round the brown wire . i found it by checking ohms on the white brown and black/yellow wires that are in that plug ( the 3 yellow wires are stator wires. just a thought
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post #4 of 61 (permalink) Old 07-15-2012, 05:47 PM
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Quote:
Originally Posted by vulcan98 View Post
i had charging problem, i found the 6 pin connector at the volt reg was cracked inside round the brown wire . i found it by checking ohms on the white brown and black/yellow wires that are in that plug ( the 3 yellow wires are stator wires. just a thought
Good thought Vulcan98 !

WilliamTech

'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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post #5 of 61 (permalink) Old 07-15-2012, 05:53 PM
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thanks and if u ever get down towards bradenton fl. look me up,
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post #6 of 61 (permalink) Old 07-15-2012, 06:39 PM
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Quote:
Originally Posted by WilliamTech View Post
Q: Are you sure the R/R has a great ground ? Was it mounted ? Place a jumper lead from R/R to negative battery terminal, then measure again. Three issues are at hand here & that would be my next effort.
WilliamTech
Bill, this idea of the r/r being grounded through the body and to the frame through the mount has been brought up before, but it is not true.
The electrical guts of the r/r are encased in epoxy and electrically (but obviously not thermally) insulated from the r/r body.
The black/yellow wire in the connector is the only ground for the r/r.

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
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TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
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post #7 of 61 (permalink) Old 07-15-2012, 07:08 PM Thread Starter
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Quote:
Originally Posted by WilliamTech View Post
I would have performed this on the + side of battery also (not believing none measured).


Q: Are you sure the R/R has a great ground ? Was it mounted ? Place a jumper lead from R/R to negative battery terminal, then measure again.
Thanks. I have also checked for current leakage on the + side of the battery, and there is none.

I am certain the RR ground is good. CORRECTION: The ground is likely not good! END OF CORRECTION

What about the rpm jump upon disconnection of RR? Is this normal and why? If not normal, does it suggest a cause for the problems I seem to be having?

Last edited by gvaughn111; 07-15-2012 at 08:41 PM.
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post #8 of 61 (permalink) Old 07-15-2012, 07:33 PM Thread Starter
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And here is some additional data for processing.

The battery is charged already. I installed and started the bike--no problem. I removed all the fuses except for the main. I then check the RR output voltages at the connector (with the connector installed). At idle, 13.5V; at high rpm 14.5V--perfect. I then check voltages at the battery posts. Too low; between 12 and 12.8 at all rpms. Rechecked at RR connector--still perfect.

For what else it may be worth, I then inserted fuses one at a time with the DMM probes still at the RR connector. When either the head or tail light fuse was inserted, the voltage dropped instantly from 13.5 to near 13. Insertion of the AUX fuse produced no effect but then I have nothing connected to this circuit. Insertion of both light fuses at the same time produced a slightly larger voltage drop at the RR connector.

Since electric circuits have mostly been a mystery to me, I have no idea if any of this is significant, but I wanted to share this with you in case it is.
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post #9 of 61 (permalink) Old 07-15-2012, 07:52 PM
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when you put the fuses back in and noticeda voltage drop, what you expirienced is normal... if the voltage climbed back up to 13.5+ after reving the engine for a few seconds.

I think you have something shorting to ground. Have you used my flow charging system flow chart? it pin points exactly where the problem is, as long as you fallow the steps in order and don't skip a single step.
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post #10 of 61 (permalink) Old 07-15-2012, 08:25 PM Thread Starter
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Quote:
Originally Posted by slimvulcanrider View Post
when you put the fuses back in and noticeda voltage drop, what you expirienced is normal... if the voltage climbed back up to 13.5+ after reving the engine for a few seconds.
Thanks. The voltage did not go back up to 13.5; it stayed at the lower number. I am familiar with your flowchart, but I did not do all the measurements yet since it seems the stator and RR are both OK. Will the flowchart help me find exactly were the bad connections is?

What am I looking for exactly? By the way, I did find a flaw in my most recent testing. I thought I had good readings from the RR ground to the battery negative post and from the RR hot lead to the positive battery post. I was in error. From the RR ground to the post, I get .6V and from the hot lead to the post I get a highly variable reading between .15 and .3V. So it would seem I do have a bad connection, probably on the ground side, but I was unable to locate any such connection the first time I went through the wiring harness. I did get some seemingly bad resistance readings, but eventually they went away and it seemed I had good continuity and good charging voltage at the battery post (14V or greater) before I put everything back together the first time.

Thanks for your help.
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