Fighting a low charging issue

67 coronet 4 door 383/727. As far as I know stock and anything that has been replaced is "oem equivalent " from parts store.
Replaced alternator after I took it in to be tested by parts store, had a dead rectifier. Installed new alternator. Only putting out 12v at idle and doesnt increase with rpm. Replaced regulator due to some corrosion coming out the back side, thought maybe the internal relay got stuck. Still no charge, car dies as soon as I pull the pos cable off the battery.
I checked resistance to the reg ground and the battery and got 0.5 ohm. Going to check the chassis ground and possibly run a new one. Engine ground is good 00ohm. Would half an ohm on the ground side cause a no charge issue?
Side note, pretty sure my battery is in the early parts of having a internal short thanks to discharging a couple too many times. Wires as I checked are low ohm, less than 0.3 across any given wire.
I know theres details I'm forgetting so please ask for what would help and I'll get an answer as I can

First can you post pictures of the back of the alternator & regulator?

There are two wires going to the alternator, the big 10 ga & a lighter ga field wire that is probably dark green.... Disconnect the dark green wire & with your volt meter hooked up to the battery & the engine running briefly jumper power from the big wire to the field terminal... It should be charging big time... If you leave it connected like that voltage will keep climbing.. So don't....

If it didn't charge chances are the new alternator is bad.. But first verify you have 12v on the big wire....

Hook the field wire back to it's terminal..

If it did charge we need to look at the regulator... There are two wires probably dark green and blue going to the regulator, same deal engine running meter connected, jumper those two wires together briefly... Did it charge?

No? verify 12v on the blue wire... If you have 12v verify the dark green wire from the regulator to the alternator has continuity...

Yes? either the regulator isn't grounding or it's bad...

Needs 12v at the blue wire at the regulator and the large output wire. Continuity on the green wire regulator to alternator. The alternator and regulator both need a good ground. Does the alternator have 2 spade connectors on the back? If so it's a later alternator. Ground one of them (doesnt matter which one). Connect field wire from the regulator to the other.
Doug

1 Wild R/T said:

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I'll have to give this a shot when I have some down time. Thank you for having that in an easy to follow manner.

It does have 2 spades but appears they are both labeled FLD. Will that make a difference?

jcskokos said:

I'll have to give this a shot when I have some down time. Thank you for having that in an easy to follow manner.


It does have 2 spades but appears they are both labeled FLD. Will that make a difference?

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No, if neither one is grounded just run a spade with a short ground wire to the case on either lug.
Doug

dvw said:

No, if neither one is grounded just run a spade with a short ground wire to the case on either lug.
Doug

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Exactly.. You have a 70 & up alternator on a 69 & down system... Ground one terminal & you should be good..

1 Wild R/T said:

Exactly.. You have a 70 & up alternator on a 69 & down system... Ground one terminal & you should be good..

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Yup. You have an electronically regulated alternator on a mechanical regulator system. Ground one brush.