Alternator warning light not always working.

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Deathacus

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Hey there! Correct me if i'm wrong, but if I turn the key to RUN without starting the engine, the charging system light should come on, right?
It has been having an inntermittent problem with not doing exactly that. I tried following the diagnostic pinpint tests in the manual, for both "not working" and "flickering/intermittent".
Here's my results: seems to behave normal when running. Grounds are good, field coil leak tests perfect. However, checking the "S" terminal, the book says it should be 0v on the wire and less than 1v on the alt. I got ~.5v on the wire and over 6v on the alt.
Reasonable sense says change the alt or the regulator, but what about the voltage through the wire?
 

BaySHO Performance

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You have the EVTM manual, right? What voltage do you get at the battery engine running? Should be 13.5-14.5 volts. The regulator is an integral part of the alternator.
 

Deathacus

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Yes, been reading the book at night like a bedtime story.

I have not measure voltage at the battery, but I have never had an issue with it not charging. Only noticeably symptom is the dashboard light itself.

Did some research between customers the other day, looks like the 'S' terminal on the alt just goes straight from the rectifier the to regulator, and it's sole job is to feed about half current when the alt is spinning, triggering the regulator to shut off the light. Since I was getting power thru there with the engine off, I can only assume a diode has failed or something, allowing battery current to back feed and shut off the light.
As for the half volt thru the 'S' wire, that wire should jump straight from the rectifier to the regulator, so it must either be damaged, or that's normal for being bundled in the same harness as other wires with power. Or maybe both my dad's Southbend and my Ames multimeters are junk.
 

Deathacus

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How do I get the old alternator out? I got both bolts, it is loose, I can wiggle it every way by hand, but it won't come out.

Side note, kinda disappointed with the color on the new SHOsource alt. Solid silver, without the black pully or the black part in the middle. I will probably keep the old pully and hope it doesn't affect my core refund.
 

luigisho

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Do you have all the wiring disconnected? Is there a bracket with a bolt on topside?
1:25 on here
 

Deathacus

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Yeah, took an hour break and had a soda then found it.
Very hidden bolt on the back side, I've seen people use it as an extra ground but did not expect it to be used as a mounting point, not very clear in the book either.
Now I hope i can get a fresh coat of paint on the pully before my starter is ready.
 

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