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Discussion Starter #1
First time posting on here hope I'm not making this to long I just want to get as many details as I can. So here we go I have a 99 vn750. Im not sure if any of this is connected but this is what I have delt with in the passed couple months. First off I notice my headlight stopped working correctly, I found the reserve lighting unit was done so I just made a jumper to bypass it. Then I crank it up one morning for work, notice my headlight was out again I try trouble shooting it for a couple mins in the dark till I get fed up. I got home checked the battery, it was done, so I replaced it. Things were fine for about a week, then one day on my way home I couldn't crank the bike the battery was dead. Started checking things realized the statue was bad, after 3 weeks waiting for the part, I swapped the stator using gse mod plate. Got it back together got it started, still no charging. Checked rectifier didn't quite check perfect, so I got a new one. Still no charging. I did notice after all that the ground wire coming directly off the frame ground that connects all the other grounds in the system was smoking. I disconnected the bullet connector, and checked things again. I could get about 13.8v at the regulator but not at the battery. Then I noticed the ground coming off the rectifier was getting to the point of melting. So I went through and figured every ground I could find. I left the frame ground disconnected, Checked one by one, from the ground in the rectifier plug to every other plug I could find. I'd check the ground, got good continuity through wire, plugged the component back in and checked to the frame all but one component checked OL but the plug that runs into the dash lights and ignition got 60 ohms. I left it unplugged tried checking to see if that was the ground/charging issue but no change. At this point I don't know what else to do, I'm at a loss, hope someone could help. Thanks in advance.
 

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Maybe a short somewhere.

Could do an amp draw test at the battery with the key off to see if there's a draw, then key on to see if draw is really high.. It shouldn't be melting the cable. ... It wasn't melting because you were cranking the starter? Make sure the cable in question is clean and tight.

In stock configuration, the headlight is triggered by one leg of the stator. If that leg fails, the headlight stays off. The Blue Wire mod bypasses this function.
 

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Discussion Starter #3
Once the bike shuts off with the key still on or not the wire starts cooling down. I had to replace the wire, because it melted the other one. It was was just the 14g wire withe the bullet connector going from the frame to the rest of the system. But I'll try the amp draw. If there is a draw what could that mean? Damaged wires or bad components?
 

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Draw with the key off would mean a short, as long as there's no clock/radio etc that draws with the key off.

Draw with key on is expected, but unusually high would be a problem. You could then start disconnecting plugs to see where the largest drop occurs.

I'm not familiar with where this 14ga ground w/bullet connector is, or what circuit, but that would seem to be the circuit with the problem.
 

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It is typically most likely to melt hot wires in short circuits and ground wires due to faulty connections. A short will overdraw protons and a lack of ground potential will struggle for electrons. Don’t concentrate On the metal, concentrate on the health of the wire as it enters the connector. They tend to corrode in the barrel.
 

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Discussion Starter #6
I just did the draw test I got 0 amps with key off. 2.33 amps keys on so nothing that high, just the tail light and dash lights. The 14g wire comes off the frame from the larger 2 or 4g wire from the battery to frame. It's the first ground from the frame to the rest of the system. Like I said in the original post I'm getting voltage from the regulator but it's not making it to the battery. Does that sound like a damaged wire that's causing too much resistance in the ground wire which causes the heat, or is it possible that one of the components are jacked up but still appear to work? Also like I said I checked all the wires best I could they all check out. There is one that doesn't seem to have a connection to the ground wire from the rectifier. I'm not sure what it's for, is there a computer on the bike.
 

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Discussion Starter #7
So I looked at the wiring diagram it's the IC igniter or 1C I have a screenshot of the part in the diagram. I checked the ground wire in the plug going to the pickup coil, I don't get continuity to ground, could that be an issue. The think is if the igniter is bad wouldn't that cause the bike not to run, or is that something to do with charging?
 

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The IC Ignitor is part of the ignition, similar to a CDI box. The pickup coils also have to do with spark.

All grounds on the bike are black/yellow, just for future reference.

Pretty sure there are tests for the IC box in the manual.
 

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Discussion Starter #9
That's what doesn't make any since to me I check for continuity on the ground wire on the plug for the pick up coil and there isnt any. But the bike runs fine other then the lack of charging
 

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In section 15-24 of the repair manual there's a chart for ohm tests on the IC. I'd go through those tests to see if the IC is ok.

edit: I recall something about the spark being triggered through ground, not sure but continuity on that ground wire may be intermittent by design. Seems the discussion was the ground at the ignition coils, so I may wrong.

You might be able to roll the engine over with the ohm meter connected at that ground, and see if there's any continuity then.
 

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Could also ohm test the pickup coils, just to rule out a problem there. Those wires are known to break.

Is the engine running on both cylinders?
 

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Discussion Starter #12
I'll take a look at the repair manual and see. Yes the bike is running on both cylinders. So the general consensus is I have a bad wire somewhere, but am I looking for a bad ground?
 

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Ok, here's a crazy theory I've been kicking around for a while regarding these bikes and why we fry so many stators/rectifiers:

Any time the electrical goes flakey, everyone immediately says "It's the ignition switch." But what nobody brings up is that the monitor wire for the R/R splits directly off of the ignition. That lead is just as likely to go bad as any other, and would cause the R/R to dump a higher-than-wanted voltage into the system, and without the protection of the 30amp main fuse. There wouldn't necessarily need to be a bad connection anywhere to have the resulting high currents start melting wires. Am I way out in crazy town with this line of thinking?

@Darren: were you able to measure voltage between the v+ and ground of the rectifier when running? What's your resistance between rectifier's monitor pin and v+ pin when engine is off but ignition is 'on'?
 

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Good post Thorn, it's got me thinking I should check the old r/r wiring on my bike, even though it's unplugged. That brown monitor wire shows up as red/white at the ignition switch (in the color diagram), but the brown runs straight there, and to the switch.

Was reading back and picked up on this ...

Once the bike shuts off with the key still on or not the wire starts cooling down.
This bike also had headlight problems .. RLU problem.

The smoking wire cools down when it's not charging. ???

If the brown at the r/r checks out ok... also check the stator wires. Maybe try the blue wire mod? That's a circuit that's only working when the engine is running and involves a relay in the Junction Box.

Could there be AC stator volts hitting some of the other JB circuits?

Could a pickup coil wire be pinched at the stator plate? If it was on the same coil with the black/yellow, would that cause it to heat up? (only when running)

Can't rule out headlight wiring yet either I guess. Your headlight is off after you shut down the engine?
 

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Yeah, the 'T' from one of the three yellow stator wires to the JB is a definite avenue for unregulated power getting into the circuitry, especially if the headlight relay has gone bad (possibly what cooked the reserve box).

HOWEVER, looking at the symptoms, I think there's a short from a live wire to the frame of the bike. After the engine has been started, current should be flowing backwards through the battery, with the current flowing from the negative terminal towards the R/R's ground wire. I suspect the thick wire between the negative terminal and the frame is that beefy in order to provide the cranking amps to the starter motor, and that once the engine is running, it is well over-sized. With a large current dumping into the frame from somewhere, though, that wire is running at capacity, and the smaller 14 gauge between the beefy wire and the rectifier can't handle the load.

A pinched positive wire near the stator does make sense, since none of the positive wires are melting, only the ground (as current dumps from the frame to the rectifier's ground/negative terminal). It would also explain why you have low/no voltage at the positive terminal of the battery since there is a better path to ground than through the resistance of the battery.

I don't think the pickup wires would have enough current to melt anything since I think they're basically just a hall effect sensor. The short is more likely one of the yellow stator wires, or maybe a short in the coil wiring itself (but that would likely cause a dead cylinder?)

When you added a jumper to bypass the RLU, which wires if any were removed and which were spliced?
 

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Discussion Starter #16
Sorry it's been so long I've been pretty busy lately. The wires I spliced together for the rlu is dark blue and blue with orange stripe.
 

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Might want to double-check if your high/low beams are reversed. I think it should be blue spliced to blue/orange instead of blue/yellow. Either way, that wouldn't be causing your ground to overheat, so the RLU seems to be unrelated to the bigger problem. If you haven't done it yet, follow Spockster's advice and do the blue-wire mod along with the optional step of removing the yellow wire from the stator that triggers the headlight relay, since that is an avenue for unregulated voltage to get into the electrical system.
 

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Discussion Starter #18
Turns out I'm a bigger idiot then I gave myself credit for. The stator I bought was carlise I believe idk if that's a cheap brand or not but apparently the screw the holds the wire strap to the armature of the stator somehow would ground out when I installed it well long story short I fried that stator bought a new one removed the screw installed it and now everything is fine. I hate that I wasted everyone's time, but thanks for everyone's help. Hopefully in the future we/I will know to check for that.
 
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