alternator buzzing
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On The Tree
Joined: May 2012
Posts: 133
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alternator buzzing I am posting this here as I am thinking it is a pcm issue.
New issue - the infamous alternator buzzing when everything is turned off, and kills the battery overnight.
Read a hundred threads with zero answer - other than to put a switch on the exciter wire.
It is not the alternator internal regulator shorting out as most reply with - tried three known good ones, including brand new.
Disconnect the red exciter wire, and buzzing stops, disconnect either battery ground or power and buzzing stops.
So key off, zero power to the pcm from keyed 12v side - Alternator exciter wire - pin 15 on the red block, is showing .420 volts and there should be nothing there at all with the key off.
Verified no power to the pcm from the 12v keyed input side, so pcm is not turned on in any way shape or form, from outside sources.
You know when the pcm has power, as several other sensors make noise firing up and the fuel pump relay turns on.
Is it possible that there is a short inside the pcm from the full time 12v power supplies via the orange wires as there is no other way for the pin 15 to be getting the .420 volts internally, that I can find?
This alternator issue is very prevalent out there from what I read and equally unsuccessfully diagnosed so far in what I read.
So hopeful someone here might have an answer that works.
New issue - the infamous alternator buzzing when everything is turned off, and kills the battery overnight.
Read a hundred threads with zero answer - other than to put a switch on the exciter wire.
It is not the alternator internal regulator shorting out as most reply with - tried three known good ones, including brand new.
Disconnect the red exciter wire, and buzzing stops, disconnect either battery ground or power and buzzing stops.
So key off, zero power to the pcm from keyed 12v side - Alternator exciter wire - pin 15 on the red block, is showing .420 volts and there should be nothing there at all with the key off.
Verified no power to the pcm from the 12v keyed input side, so pcm is not turned on in any way shape or form, from outside sources.
You know when the pcm has power, as several other sensors make noise firing up and the fuel pump relay turns on.
Is it possible that there is a short inside the pcm from the full time 12v power supplies via the orange wires as there is no other way for the pin 15 to be getting the .420 volts internally, that I can find?
This alternator issue is very prevalent out there from what I read and equally unsuccessfully diagnosed so far in what I read.
So hopeful someone here might have an answer that works.
