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aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

Voltage regulator or alternator?

About an hour ago my car ('95 Bronco) suddenly stopped charging (luckily the battery had enough juice to get home) and I'm trying to figure out if it's the alternator, or the voltage regulator -- based on that it just died w/o any warning, I think the main suspect is the regulator. Looks to me voltage regulator is actually attached to the back of alternator.

Where and what should I measure to find the culprit?
If I buy a new alternator, will it come with a voltage regulator, or that's a separate item?

TIA
--
Wacky Races 2012!



Juggernaut
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join:2006-09-05
Kelowna, BC
kudos:2

They're integral these days. And yea, it's probably the regulator. Get a reman, and call it a day.
--
Better to have it and not need it, then need it and not have it.



shdesigns
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reply to aurgathor

Measure the battery voltage.

On the regulator are two terminals. One is marked "ground to test". Ground it momentarily (at idle only) and you should see the battery voltage go up. Test the other terminal with a meter, you should get battery voltage.

If the voltage goes up grounding the terminal, you likely need a new regulator.
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Embedded Systems Consultant,
SHDesigns home - DIY Welder



mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3
reply to aurgathor


That regulator is not integral, and it can be replaced separately. It screws onto the back of the alternator frame and also holds the brush set for the alternator.

A competent shop with an alternator test unit can determine if the regulator or alternator is the problem. There are also voltage checks that need to be made. If you want to gamble with 40 bucks or so, you can do a "parts swap diagnosis" and replace just the regulator and see if that was the problem.

Obviously that isn't how I would do it, but it could be worth your while to take the gamble. Those regulators were not an uncommon failure.



Juggernaut
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Kelowna, BC
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1 recommendation

Thanks for the correction, Matt.



mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3

said by Juggernaut:

Thanks for the correction, Matt.

Not a correction, just clarification.

They're a dying breed for sure, and honestly, your advice to just replace the whole unit with a reman is actually the best for a DIY situation.


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
reply to shdesigns

said by shdesigns:

Measure the battery voltage.

On the regulator are two terminals. One is marked "ground to test". Ground it momentarily (at idle only) and you should see the battery voltage go up. Test the other terminal with a meter, you should get battery voltage.

If the voltage goes up grounding the terminal, you likely need a new regulator.

I just took it out a couple of minutes ago, and yes there is an arrow pointing toward a torx headed screw (I guess that connects the terminal) and with a message ground to test.

Hopefully I can test it before it gets completely dark, or the rain starts falling.
--
Wacky Races 2012!


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

And the end result is: None of the above!!

I put everything back, hooked up a DVM, started the engine -- and no battery light! Checked the DVM - 14.50V!! And I didn't even take the connectors off, which could've meant a corroded connection.
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Wacky Races 2012!



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

Click for full size
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Update: the 'self-healed' alternator apparently didn't last very long -- it was still working fine when I went to work, but stopped working again when I was coming back.

After I got home I did the grounding test -- no change whatsoever, so I went out and bought one in the nearby O'Reilly. Since I had to replace it anyhow, I decided to upgrade to a 130A alternator instead of a 95A by telling the salesman that I need it for a '95 Explorer.
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cdru
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Fort Wayne, IN
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said by aurgathor:

Update: the 'self-healed' alternator apparently didn't last very long -- it was still working fine when I went to work, but stopped working again when I was coming back.

I had a Talon that had a similar problem once upon a time. Failed while on the vehicle. Took it in to the parts store and it tested fine. Reinstalled, it failed a day or two later. Couldn't figure out what was failing so we took it in to a shop and they pulled it and it tested fine. Reinstalled with a note of no fault found. It failed a few days later. Went back to the shop a 2nd time for the 3rd removal. Same thing happened where it tested fine on the bench. This time they beat on it a few times and retest and it failed.


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

I'm planning to take it apart for a post-mortem -- that may reveal what failed. Given the nearly 280k on the vehicle, I'm guessing that the brushes may be worn out, although there are several other possibilities.
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Wacky Races 2012!



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

Click for full size
The brushes are completely worn out, and the commutators aren't far behind. (it may be hard to see, but there are some deep grooves in there) So it was an end of life wearout.

BTW, he bearings are still in excellent condition.

Don't know anything about the cdru's Talon's alternator, but removing the brushes was a piece of cake in this case -- much less hassle and effort than taking the whole thing to the parts store for testing.
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Wacky Races 2012!


Juggernaut
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Kelowna, BC
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Thanks for the post-mortum. Burnt commutators, and a 'Grand Canyon' there.
--
Better to have it and not need it, then need it and not have it.



shdesigns
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reply to aurgathor

I used to rebuild alternators. Brushes usually don't wear out.

The most common cause was oil leaking from a power steering pump getting in to the alternator. Could be oil, or some other contaminant gettting to it (it does look real corroded.)



Cho Baka
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join:2000-11-23
there
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said by shdesigns:

I used to rebuild alternators. Brushes usually don't wear out.

The most common cause was oil leaking from a power steering pump getting in to the alternator. Could be oil, or some other contaminant gettting to it (it does look real corroded.)

This is it exactly. If there are any oil leaks in the vicinity, fix them now.
--
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aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

There are many minor oil leaks (most easily visible on the underside), but looking at the alternator, it's not getting there.
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Wacky Races 2012!



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
reply to shdesigns

said by shdesigns:

I used to rebuild alternators. Brushes usually don't wear out.

I'd tend to think they'd be the first thing to wear out, but what may happen is that alternators can fail for other reasons well before that happens.

The most common cause was oil leaking from a power steering pump getting in to the alternator. Could be oil, or some other contaminant getting to it (it does look real corroded.)

While the commutators look bad, I think what happened there is arcing that burned one very badly. The brushes actually wear down to the copper connecting wire.

I actually bought a a set of brushes a couple of years ago, but never put them in.
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PeeWee
Premium
join:2001-10-21
Madera, CA
reply to aurgathor

You should check for breaker, fuse or fuse link first.



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

Click for full size
I'm not sure how much of the relevant input/output is fused, either with fuses or with fusible links, but once it's known that the alternator is not charging, one should start with these:

1) ground the test point and check the output voltage for change.
2) If there's no change, check if there's Vbat on the other terminal
(I removed the connector, and checked for Vbat there, but I presume the plastic cover is over the other terminal to prevent accidental grounding)
--
Wacky Races 2012!