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rider
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213 Posts
Discussion Starter #1
91 Vulcan 750; 23k miles.

My battery isn't charging and i've been following www.electrexusa.com/Images/fault_finding.pdf to diagnose the issue. The first two R/R voltages checked out, but when checking the switched +12V wire leading to the R/R, i'm getting a reading of .84V (.2V is allowable according to the flowchart). This leads me to:

'Bad connection from the battery(+) through the ignition switch to the switched +12V supply-input on the R/R. Check the whole electrical circuit. This is one of the most difficult faults to find [YAY!!!]. Suspect the ignition switch itself, the fuse-box and its connections. ...]

I've cleaned all of the fuse connections, the junction box connections, the battery leads, and the connections in the headlight enclosure. Nothing I've done has brought the reading down.

So... I should suspect the ignition switch? Are there any other problematic connections I should check? Has anyone had this issue and resolved it by replacing the ignition switch? Someone please give me some hope. I generally hate smilies, but :BLAM: fits perfectly.

Thanks.
 

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and the Adventure Cycle
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6,141 Posts
There is a post in the Vulcan Verses about the ignition switch.
You can check it out HERE.
Sorry I can't be of more help to ya on this.
 

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Once Banned
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2,125 Posts
Hopefully.

I read thru the Fault pdf file; did you follow the wire to see what voltages at what places? That should tell you where the extra resistance is.
 

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rider
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213 Posts
Discussion Starter #5
cegodsey said:
Hopefully.

I read thru the Fault pdf file; did you follow the wire to see what voltages at what places? That should tell you where the extra resistance is.
no... but that's a good suggestion. i'll do that tomorrow (er, today) after i reinstall the ignition switch. thanks!
 

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Registered
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90 Posts
Another likely sourse of the resistance is the cable itself, specially those near heat sources such as the R/R. Check the resistance of the cables between the R/R and the juction box, both the positive and the ground cables coming from the R/R are a bit small for the rated current of the charging system.
My 93 Vulcan requiered a splice of new cable between the positive lead of the R/R to the juction box and from the ground lead of R/R to the ground post of the battery.
Doing this eliminated all the parasitic power loss on the cables.
Hope this helps
 

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rider
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213 Posts
Discussion Starter #7
here's the latest:

after removing, cleaning, and reinstalling the ignition switch (completely stripping and breaking off one of the tiny screws that holds it in place... DO NOT OVERTIGHTEN THESE SCREWS) as well as cleaning all of the electrical connections right in front of the gas tank, the reading from the switched input of the R/R and the positive battery came down to .59V (from yesterday's reading of .84V). so, i'm making some progress... but i'm still not down to the .2V that the fault finding pdf stipulates. as a recap, i'm measuring the voltage between the switched lead of the R/R to the positive battery terminal.

cegodsey ['did you follow the wire to see what voltages at what places? That should tell you where the extra resistance is.']: the brown wire (switched lead) that comes out of the R/R disappears into the main bunch of wires and heads up towards the headlight. i can't really make sense of the electrical diagram in the manual, but it looks like it re-emerges in a connector in the headlight enclosure... tried a reading there and got .62V. are there other place i can measure?

mushu ['Check the resistance of the cables between the R/R and the juction box']: thanks for the suggestion... but again, i'm having difficulty tracing those wires. the positive and negative R/R wires disappear in the main bunch of wires and i head up to the headlight. it doesn't look like those wires go right to the junction box. which wires exactly did you replace?

one other bit of positive news... i checked the AC volts coming off the stator leads and i'm getting 78-80V across all three leads when the engine is running at 5000rpm. given that and my resistance readings, i'm assuming the stator is fine. i ordered a new R/R which should be here wednesday. if i can just get that switched lead of the R/R to the positive battery terminal down to .2V i'm hoping i'll be good to go.

thanks to everyone who has responded so far... really appreciate it.
 

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Once Banned
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2,125 Posts
GREAT NEWS! Don't drive it until you get the new r/r. And if for some reason you have to, disconnect the r/r.

I'm just guessing at this, but there is a chance that the fault.pdf is referring to voltages much greater that .2V.

As to following the diagram, it looks like there are a couple of connectors between the r/r and the ignition switch. One is for the rear brake light switch and junction box, and the other is front brake light, tach, and horns. Chances are that the extra resistance is coming from a connector, Although that value is low enough it could just be excess low gauge wiring. What gauge wire is it?
 

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90 Posts
I'll post some photos later today so you can see what I did to fix this problem... check back later and I hope this helps...

Martin
 

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rider
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213 Posts
Discussion Starter #10
cegodsey said:
I'm just guessing at this, but there is a chance that the fault.pdf is referring to voltages much greater that .2V.
i thought about that as well... that's what i'm hoping.

cegodsey said:
What gauge wire is it?
i can't find the gauge written on the wire... i'd guess 14.

Mushu said:
I'll post some photos later today so you can see what I did to fix this problem... check back later and I hope this helps...
that would be fantastic, martin. i'd appreciate it.
 

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rider
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213 Posts
Discussion Starter #11
oh hell yea! check it out:

batteryvoltage.jpg

i installed the new regulator today (well, plugged it in anyway)... and the battery voltage is 14.5v when the engine is at 5000rpm. i think that does it!

a few things...

1. thanks to everyone who provided input here... i REALLY appreciate it.

2. now that i solved (well, hopefully) this problem i feel so much more confident working on my bike. yes it took some time, but i saved money and i'm much more knowledgeable about the vn750's electrical system.

3. martin/mushu... if you have time and the inclination, i'd still be interested in seeing what you did with the wires going to the R/R.

4. i'm most likely going to relocate the R/R as advised by this group and i think i may also fuse the stator leads (saw the recent post that 7.5 amp fuses would work best). will these fuses prevent the biggest cause for stator failure?

thanks again everyone!
 
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