phantom draw, sparks, things are blowing up

[frwinks]

I had a phantom draw that was killing my batteries which I narrowed down to a plug that goes into the alternator housing. It's the same plug that houses the oil sensor and neutral switches on the 81/82 sj (thanks for the color diagram jayel )
When I plug and unplug this connection I get a spark on the green and brown wires, which seem to be live even with the key off.
Last thursday, while riding home from work, I lost the left cylinder (no spark, but coil is good when swapped to the other side), burnt headlight bulb, and a burnt taillight/stop light. All fuses are still good
Does anyone know what those two wires go to in the alternator housing ( I boxed in the part on the pic) My guess is that whatever it is, it's sucking the battery juice, took out the regulator and sent a fireball and fried the lights and possibly the cdi, since it's not sending a signal to the left coil....
Am I on the right track here

 

[drewpy]

just checked the Yam manual and it's the field coil, it gets juice and creates a magnetic field, which inducts into the stator.
disconnect the plug and get a multimeter should be 4 ohms +/- 10% @20'C

stator is .72 ohms +/- 10% @ 20' c

 

[CadXS]

The green and black wires are there to provide a feed to the field coil in the alternator (I think ). It's the smaller inner coil inside the alternator housing and you should be able to see the two wires connect to the coil by taking off the round alternator cover. The field coil needs to be excited for the alternator to work and its controlled by the output of the voltage regulator. The field coil needing a battery to excite it is why you cannot run the XS400 with no battery. If the voltage regulator which controls the alternator output is fried then this could cause some electrical damage as it is there to provide a constant supply of current and not to be effected by engine speed.

Not sure if that helps (or is even correct, lol ).

Check your voltage regulator and alternator output (and rectifier, why not?).

Which voltage regulator do you have? Is it the little silver box solid state one on the SG?

 

[frwinks]

thanks for the tips gents
yes, I have the small silver regulator. I took care of the phantom draw last night, had the wrong wire hooked up to my new fuse block
Will check the readings tonight, thanks

 

[frwinks]

ok, so the field coil came up @ 3.6ohm
the stator @ 1.4ohm
the recitifier @ no reading @ all
the regulator I can't check unless the bike is running correct?

Since the rectifier is done, is it safe to assume that the regulator is cooked as well? The stator reading seem high as well @ twice the recommended value.

Are there "off the shelf" replacements for the rectifier and regulator ie. I read some Chrysler rec or reg. can be installed on the 650's. Would they work on the 400

the bike ran like a champ before all this, I put almost a 1000km on it in less than a week hurts me seeing it all torn apart in the barn

 

[drewpy]

regulator is checked by the battery terminals on DC. 14.5 volts @ 3k revs.

rectifier should be tested by alternating the input/output on the connections. that is, electric will only "flow" one way, so you'll get no output on two wires, swap round the +/- on the multimeter and then you will get a 12V reading.

Its like a one way gate, can only flow one way and can't flow back!

you can do this on all the wires on the rectifier

 

[bcware]

When one of my alternator wires was cut in the past it read something above 1 ohm. Normal should be about 0.7 ohm and I did not see any significant variation with temperature (10% of 0.7 is only 0.07). Are all 3 wires measuring 1.4? Are you taking the reading correctly? From the plug harness you should be checking the yellow wire against each white wire, one at a time.

Drewpy is right about the rectifier; you should get no reading in one direction.

I don't know about any "phantom draw," but it sounds like your bike is simply not charging because one of those wires going to the alternator is cut somewhere along the way. This happened to me because the harness got pinched by the left-hand-side sprocket/clutch pushrod cover. From this cover the wires go into the left hand case.

There may be some color variation in the wires for your year compared to mine. Are you using the testing procedures in the manual?

 

[frwinks]

thanks for the feedback guys...all uncharted waters fer me here
I'll test the rectifier again, as I'm pretty sure I messed up the procedure.
My alternator only has three wires, and you're right bc, two of them were pinched by the clutch cover, but not cut. I peeled the sheathing off and the wires are still ok. Yes, I'm testing "in pairs" as per the manual.

The phantom draw was a wrong brown wire hooked up, bypassing the main switch and constantly feeding the field coil. I fixed it thanks to jayel's diagram...

 

[frwinks]

not getting any action out of the rect.
1)red meter probe to red wire, black probe to each one of the remaining wires=no reading(manual says should have reading)
2)red meter to black wire, black probe to each of the remaining wires=no reading(manual says should have reading)
3)reverse the probes on the meter and repeat 1 and 2=no reading(manual says should NOT have reading)

 

[bcware]

Is your multimeter set on the right scale for resistance? Just checking

 

[drewpy]

I put my multimeter on 12v sounder, this sends 12v through the wires!
a battery and bulb would do the same thing

 

[frwinks]

I set it @ the lowest ohm setting...200 and yes I got 1.4 ohm on all three wire pairs

I'll play around with the below test tomorrow, see if I can get some readings and report back

[/QUOTE]

thanks guys

 

[frwinks]

the results are in no readings on two tests, some .4's on the other two

 

[frwinks]

took a short clip of the culprit in the act...this is the battery voltage when I plug in the voltage regulator... my guess is, it's not supposed to drain the battery that much...whaddya think?

 

[drewpy]

As the diagram says, R/R is at fault, replace!

 

[frwinks]

turns out I had more issues than I thought....story of my life
I found the rubber boot over the starter cable shorting out on the case while ripping the starter out to make the bike kick only and eliminate as much wiring as possible.

After fixing the boot issue, I kept the starter and installed a new/used RR, starter solenoid, cdi box and all seems to be running fine for now.