Voltage regulator

[mikalkouki]

do the rb motors have internal or external voltage regulators? I have two alternators (one that came off of an rb that maintained voltage regularly) and both of them aren't putting out anything, however it's got 12v on the terminal and chassis ground to the screw in the back and all fuses are good.

[240z4u]

internal, do you have power at the field wire?

[mikalkouki]

field wire? would that be the brown plug on the alt? it is getting 12v to the main bolt on the alt

[240z4u]

No, thats not the field wire.

Brown plug like you said. Look at the schematic and test it for voltage. No power there = no charge.

There is a fuse for it under the hood, 7.5a I think. check that first.

[Darius]

Make sure your 7.5A ALT fuse is in the proper slot and isn't blown.

[mikalkouki]

so the field wire is not getting any voltage and all the fuses are in place and in good condition. both 7.5a fuses are getting 12v. However the 75a fuse is getting 12v on both sides with the fuse out??? Would I be able to just run a hot wire to the field wire? I have one white/red and one light green wire in the plug... if so, which one is supposed to be 12v and is the other a ground?

[Darius]

If both sides of the 75A fuse are getting power, there is a power backfeed somewhere.

[krayton]

im a noob with this stuff.

can someone explain what the plug on the alternator is?

you have the big power wire, a small ground, and that plug.

where does that plug go/do?

[mikalkouki]

how would I go about testing or troubleshooting this backfeed issue?

[Darius]

It simply means that you are getting power fed from the body or engine harness somewhere before the fuse box. It should go battery>fuse box>body/engine harnesses. If you have power on both sides of the 100 or 75A fuse, then power is somehow getting from the battery>engine/body harness without passing thru the fuse first.

Do you have a system in the trunk or something that would have power from the battery and battery power is spliced off to something else on the body harness from the stereo?

I believe the plug is for the regulator fuse and indicator light circuit for the dash. If you pull the 7.5A fuse for the alternator, the dash light will come on. I'm assuming that the same would happen if the plug was pulled out of the alternator too.

[mikalkouki]

I do not have a separate system in the trunk... I can't figure out what is causing this and before the swap the alternator worked fine (although I don't know if the backfeed was there then). All I have figured out so far is that there is no continuity between the two prongs under the 75a when the battery is disconnected, however there is when the battery is connected. Ultimately would this cause my alternator to not charge?