Low Volts
Thread Starter
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Elder User
Joined: May 2009
Posts: 514
Likes: 3
From: Long Island
Got slammed with more snow and ice. Going to try and get outside tonight or tomorrow and check for voltage. Can anybody tell me where the voltages from those two pins on the connector come from?
Trailering
Joined: Dec 2009
Posts: 22
Likes: 0
From: Usa
I'm having the same problemas 429popweredf350. I have an 06 kingranch 6.0l stopped charging yesterday. voltage at pigtail is 12.0 at both terminals( I thought exciter wire was supposed to 1-3v koeo) same as at bat(whether koeo or koer. ). battery light in cluster did not light up when alt stopped charging. and does not light(very very dim flickering) with koeo. im sure the alternator is bad .but I am sure there is an underlying issue that needs to be addresed. truck just came back from dealer for injector replacment so i checked wiring harness for damage appeared okay .( both batts less than 1month) anybody else experiance this or can point me in the right direction especially as to the issue with the dash light? thanks in advance Dan.
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
This is the wiring diagram for the alternator.
Pin 1 (light green with red wire) is the I circuit and goes to the charge indicator light in the instrument cluster. The cluster powers this circuit when the glow plugs shut off, which switches on the alternator.
Pin 3 (orange with light blue wire) is the A circuit. This is the voltage sense circuit, which is used by the regulator to determine voltage, and is also used to power the alternator field coils.
Pin 1 (light green with red wire) is the I circuit and goes to the charge indicator light in the instrument cluster. The cluster powers this circuit when the glow plugs shut off, which switches on the alternator.
Pin 3 (orange with light blue wire) is the A circuit. This is the voltage sense circuit, which is used by the regulator to determine voltage, and is also used to power the alternator field coils.
Trailering
Joined: Dec 2009
Posts: 22
Likes: 0
From: Usa
so pin 1 should only have voltage after the glowplugs have cycled? and that would control the bat light? I cut my green wire and still had 12.0 v keoeo and koer and no bat light in dash. i checked all instrument cluster fuses. all good. unless i am missing a fuse somewhere. really scratching my head on this one?
Trailering
Joined: Dec 2009
Posts: 22
Likes: 0
From: Usa
excatly pin 1 has bat voltage koeo and koer .engine can run for 30 secs or 20 mins. same result. I am alost sure the alt is bad. but i think there is a more serious issue. with the bat voltage at the exciter wire and no bat light in the dash? so before I replace the alt I have to figure this out because it is most likely what caused the alt to fail.
and i really appreciate the help and insight.
dan
and i really appreciate the help and insight.
dan
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
I'm not sure you necessarily have any other problem than the alternator. The only time the I circuit shouldn't have power is when the glow plugs are on. While they can be on up to 2 minutes, they may not come on at all if the engine is already partially warmed up.
I've also read of any number of cases where the alternator has failed and the battery light has not come on. I can't say I really know why that would happen but it appears that it does.
I would have the alternator tested first. The regulator has probably failed.
I've also read of any number of cases where the alternator has failed and the battery light has not come on. I can't say I really know why that would happen but it appears that it does.
I would have the alternator tested first. The regulator has probably failed.
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Trailering
Joined: Dec 2009
Posts: 22
Likes: 0
From: Usa
yes but the I circuit has power(approx 12v) even while the glow plugs are on. and I have read that the voltage should only be (koeo 1-3v koer approx 9v). and I am afraid that when I change my alt. that it will work, only to fail because of the excessive voltage at cir.I.
thanks again Dan
thanks again Dan
Thread Starter
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Elder User
Joined: May 2009
Posts: 514
Likes: 3
From: Long Island
Well, reinstalled the alt. that 2 auto parts stores said was good. Ran all the tests in the technical service manual TWICE and all voltages were correct where indicated. Left it idling for about 1/2 hour. It stopped charging on 2 different occasions. Each time I gave the alt a couple taps with th wooden handle on my hammer and it started charging again. Right now, it's charging normally. Tomorrow I'm ordering a new alternator. I'll let you know when it arrives if it fixes my issue.
Thread Starter
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Elder User
Joined: May 2009
Posts: 514
Likes: 3
From: Long Island
UPDATE
Just to give everyone who contributed to this thread an update, I replaced the alternator on Saturday and she's been running flawlessly for 2 days. I guess it just goes to show that sometimes you should trust your instincts and not always the machine at the local parts store. I followed the procedures in the service manual to the letter and both times, the voltages tested as per spec. The diagnosis was replace the alternator. I pulled it and had it tested at the local auto parts store and they told me it was good. I went to a second auto parts store for a second opinion and again the alt passed. I reinstalled it and continued to have the same problem. Instead of chasing my tail, I trusted my instincts, bucked up and spent the $250 and replaced the alt and low and behold..........problem solved.
Thanks everyone
Thanks everyone
Senior User
Joined: Jul 2005
Posts: 449
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Jerry, glad you got it fixed, good instincts on your part. I had a similar event with my batteries, tested good at 2 shops but still tough to start and reading low, went directly to the Interstate Battery outlet and they said they in fact were both bad.
Thanks for updating us on how it turned out.
Thanks for updating us on how it turned out.
