Alternator Wiring Question
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Postmaster
Joined: Mar 2007
Posts: 2,612
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From: Dunwoody, GA
Alternator Wiring Question
My alternator quit charging last night. Was pretty much a sudden onset as I was driving down the road and left off the accelerator the battery light came on and lights dimmed a bit. When I stepped on the accelerator again they bat. light went off and the lights came back up.
At idle I'm at 11.77v. I've pulled the plug on the back of the alternator and I'm getting voltage on both the red and green wires that go into the plug with the engine running. Is this correct?
At idle I'm at 11.77v. I've pulled the plug on the back of the alternator and I'm getting voltage on both the red and green wires that go into the plug with the engine running. Is this correct?
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
The Field and the org/blu need 12v. I believe it is very important that the field wire has at least battery voltage (no voltage drops), it has something to do with charging the outer windings and being a reference voltage. There is possibly a fuseable link on this wire, compare the voltages on the this wire at the alt and the case vs across the battery.
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Postmaster
Joined: Mar 2007
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From: Dunwoody, GA
Thanks. The voltage was correct on both feeds. I pulled the alternator and replaced it with one from a junk yard. My voltage is back up to 13ish. Got to send in this 200amp HD to be repaired under warranty. So glad this didn't happen a couple months from now.
New User
Joined: Jul 2009
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Electrical Problem
I have read every one of the threads on the battery, alternator issues. I have 1 question on this particular thread. If the Field and the org/blu need 12v, do I check this with the plug pulled off and the engine running or do I test the plug while the engine is running and the plug attached to the alternator? I am really pulling out my hair on this one. I have put on a new alternator and installed 2 new batteries and the idiot battery light will not go out. I am only getting 14.1 volts on my fluke. I have a 1999 F350 SD with a 7.3 diesel.
New User
Joined: Jul 2009
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After reading my posting, I didn't make it clear on the reading. I am getting 14.1 volts on the battery posts, not on the alternator wires and after reading some of the previous posts, i was wondering if I had a blown fuse link some where.
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Tuned
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Tuned
Joined: Jul 2007
Posts: 338
Likes: 1
From: Barbourville Ky
just went back and reread your post.I think I have an answer to your question.just because the alternator will bolt up and plug in correctly ,,doesnt mean it will work.
the alternator that reax has pictured is the 6g or six generation ford alternator.I know of 4 different regulators that will fit in this alternator.(they WILL NOT interchange)the regulator in your alternator is probably the wrong one for your truck.before you go to digging into your harness try another unit.I own an alternator rebuild business and have run across this problem several times.
the alternator that reax has pictured is the 6g or six generation ford alternator.I know of 4 different regulators that will fit in this alternator.(they WILL NOT interchange)the regulator in your alternator is probably the wrong one for your truck.before you go to digging into your harness try another unit.I own an alternator rebuild business and have run across this problem several times.
Postmaster
Joined: Jul 2004
Posts: 3,156
Likes: 0
From: Yuba City, CA.
just went back and reread your post.I think I have an answer to your question.just because the alternator will bolt up and plug in correctly ,,doesnt mean it will work.
the alternator that reax has pictured is the 6g or six generation ford alternator.I know of 4 different regulators that will fit in this alternator.(they WILL NOT interchange)the regulator in your alternator is probably the wrong one for your truck.before you go to digging into your harness try another unit.I own an alternator rebuild business and have run across this problem several times.
the alternator that reax has pictured is the 6g or six generation ford alternator.I know of 4 different regulators that will fit in this alternator.(they WILL NOT interchange)the regulator in your alternator is probably the wrong one for your truck.before you go to digging into your harness try another unit.I own an alternator rebuild business and have run across this problem several times.
Thread Starter
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Postmaster
Joined: Mar 2007
Posts: 2,612
Likes: 2
From: Dunwoody, GA
if he is getting 14.1 volts at the battery though it would seem that the alternator is charging. The batteries shouldn't hold a charge at 14v while the alternator isn't charging.
Tuned
Joined: Jul 2007
Posts: 338
Likes: 1
From: Barbourville Ky
On newer charging system the charge rate is determined by a voltage "sense" circuit.Example.when you turn headlights on you naturally have a voltage drop.the body control module senses this drop and sends a signal to the voltage regulator and tells in to step up charge rate to make up for the drop.the problem encountered here could be the fact that the regulator in the alternator is not compatiable with the rest of the truck.
Chances are that with no load he has 14.1,but i would say that if he started turning things his voltage would drop like a rock.
Also I will throw this one in for free.Under no circumstance should the battery cable be removed with the engine running.This was a common pratice on older model systems.This is a definate NO-NO on newer charging systems.The reason is because you have no voltage control and can send a voltage spike thru your entire system and can burn up more stuff in a few seconds than you can afford to fix with several paychecks.
Tuned
Joined: Jul 2007
Posts: 338
Likes: 1
From: Barbourville Ky
Yes,if there is anything the folks on the board need I would be glad to send it to them.
Postmaster
Joined: Jul 2004
Posts: 3,156
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From: Yuba City, CA.
Thanks for your valueable insight. I replaced my alternator a couple of weeks ago and would like to rebuild my stock one. I'll make sure I send you a pm when the time comes, thank you.