Parasitic draw on FLD wire to alternator

[Mybronc]

I have found a parasitic draw at my alternator. I used the test light method on the negative post and negative cable. My 74 has a stock type alternator with external regulator and new painless wiring. After checking all of the fuses, to no avail, I moved to the alternator. The light goes out when the FLD wire is removed from the alternator. My question is: is the problem with the alternator or the regulator or something else? What do I replace? Thanks for any help.

 

[broncnaz]

Do you have power at the fld wire when its unhooked? key off of course. If so then its probably the regulator.

 

[Mybronc]

The FLD wire (unhooked) does have power with the key off.

 

[Broncobowsher]

Do you have power on the "I" wire on the regulator?

Yes, you have bad wiring keeping the charging system alive
No, regulator is bad

 

[Mybronc]

Ok, no power to the I terminal (no wire attached per painless install instructions). So, it sound like a bad regulator. I'll replace the regulator and post an update. Thanks for the help.

 

[Mybronc]

I replaced the voltage regulator today with a new VR and bolts and it fixed my parasitic drain. I do have another question though. When I had placed the original regulator back in the bronco with the new wiring, I had used different bolts. I noticed today that the bolts were not magnetic and my firewall is lined with bedliner. Do you think the whole problem was just not having a proper ground?

 

[broncnaz]

That could have been the issue. Reisntall old regulator and see what happens.

 

[Broncobowsher]

bad ground to the regulator will blow the regulator. It is already shot. Make sure the body of the new regulator has a good ground or it will die as well.

 

[DirtDonk]

Ditto that. Grounded to the body, but ALSO run a small ground wire between one of the bolts and a point on the case of the alternator. There are actually a couple of "GRD" studs back there, but any point on the case will do the job.

Paul