s6 alternator case shows 12volts on casing.
11-24-09, 08:46 PM
#1
s6 alternator case shows 12volts on casing.
Got a question for you guys. I've got an s6 alternator and today I was tightening my alt belts and when I unscrewed the adjuster bolt I noticed small sparks when I would move it around. So I took voltage readings on the screw and it was 12 volts. Then I took readings of the alt case itself and sure enough it had 12volts. I went ahead and unplugged the s terminal and the voltage went away. Anyone know what the deal is?
11-25-09, 08:04 AM
#4
HAILERS
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The ground circuit for the internal electrical circuits of the alternator is........the case of the alternator bonding with the engine case. Makes sense to me seeing voltage b/t the alt case and the engine.
11-25-09, 08:33 AM
#5
Hey hailers, long time no talk to. Was hoping to hear from you 
So right now if you were to go outside to your car with a multimeter and touch the alternator with the possitive lead and then touch a ground with the negative lead, you would see 12 volts?
So right now if you were to go outside to your car with a multimeter and touch the alternator with the possitive lead and then touch a ground with the negative lead, you would see 12 volts?
11-25-09, 10:39 AM
#6
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If my alternator is bolted down to the engine I would not expect to see more than something like .02vdc. If the alternator was laying on some rags etc and not bolted down I'd expect to see ?? maybe what your seeing.
Never done that. Might do it for fun when time allows. But I KNOW the electrical devices inside the alternator, like the regulator internals, get gnd from the body of the alternator making contact with the engine block which in turn is grounded to the battery through the large negative batt cable being bolted to the staters long bolt or one of the other engine/transmission bolts.
I MIGHT do this fiddle around thing sometime when time allows.
On a series four I would not expect to see it with the key off, but on a series five/six there is a HOT wire coming from the EGI fuse which is hot 24/7 days a week. On series four its got a switched voltage to the regulator and shows up only when the key is to on or better.
I think this is like the lead or trail coil assy's. Their internal elect circuits also get gnd only if the assy's are bolted to the chassis. You can unbolt a coil assy and lay it on some rags. Then with the key ON, try to reinstall the coil assy and when you do you'll see sparks when the assy mates with the studs that hold it on. Coil assy's won't work if not bolted to the chassis with at least one stud holding it on. Lay it on the rags and it can't work at all.
Never done that. Might do it for fun when time allows. But I KNOW the electrical devices inside the alternator, like the regulator internals, get gnd from the body of the alternator making contact with the engine block which in turn is grounded to the battery through the large negative batt cable being bolted to the staters long bolt or one of the other engine/transmission bolts.
I MIGHT do this fiddle around thing sometime when time allows.
On a series four I would not expect to see it with the key off, but on a series five/six there is a HOT wire coming from the EGI fuse which is hot 24/7 days a week. On series four its got a switched voltage to the regulator and shows up only when the key is to on or better.
I think this is like the lead or trail coil assy's. Their internal elect circuits also get gnd only if the assy's are bolted to the chassis. You can unbolt a coil assy and lay it on some rags. Then with the key ON, try to reinstall the coil assy and when you do you'll see sparks when the assy mates with the studs that hold it on. Coil assy's won't work if not bolted to the chassis with at least one stud holding it on. Lay it on the rags and it can't work at all.
11-25-09, 01:13 PM
#7
Ok thanks for the explination. I noticed it happening when I went to put the adjuster bolt back so I could tighten the belt and then the bolt. When I would slide the bolt through to the alternator it would spark (not bad just small sparks). This morning I went ahead and tightened the belts and adjuster bolt and the voltage went away. I guess the large bolt going through the bottom of the alternator and engine isn't enough to ground the sucker? Strange, I'd just never seen that before. Thanks again man.
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