Alternator short circuit

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richardson.randall@gmail.com - 20 Jul 2006 01:47 GMT

I have a 1993 Volvo 240 wagon. I just replaced the alternator, but when
it came to connecting the wires I ran into problems. Every time I
attach the battery cables I hear sparks and the alternator goes 'pop'.
I'm guessing that there's a short circuit, but I'm not sure how to fix
it. I connected the wires to the terminals as follows (Thick red to
B+, Thin red to D+, Thick green to other terminal)

I disconnected the green wire and clipped the negative end of my
voltmeter to it. Then I touched the positive end to the alternator. The
entire alternator was electrified, even though the car was turned off.
Is this normal?

Is there something else I'm supposed to know about connecting these
wires?

Any help would be appreciated.

Thanks,
-r

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Mike F - 20 Jul 2006 13:23 GMT

> I have a 1993 Volvo 240 wagon. I just replaced the alternator, but when
> it came to connecting the wires I ran into problems. Every time I
[quoted text clipped - 15 lines]
> Thanks,
> -r

Thick green is probably blue, and is the ground connection since the
alternator is mounted in rubber bushings. connect this wire to one of
the long screws that hold the front and back halves of the alternator
together.
The alternator is connected directly to the battery (through the starter
motor terminal), it doesn't drain the battery due to the diodes.

Signature

Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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richardson.randall@gmail.com - 21 Jul 2006 01:23 GMT

Mike,
Thanks for your reply. As far as the entire alternator being charged
when the key is in the off position, is this a normal thing? I'm
wondering if maybe the alternator I put in is the problem?

> > I have a 1993 Volvo 240 wagon. I just replaced the alternator, but when
> > it came to connecting the wires I ran into problems. Every time I
[quoted text clipped - 29 lines]
> Replace tt with t (twice!) and remove parentheses to email me directly.
> (But I check the newsgroup more often than this email address.)

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Mike F - 21 Jul 2006 13:20 GMT

> Mike,
> Thanks for your reply. As far as the entire alternator being charged
> when the key is in the off position, is this a normal thing? I'm
> wondering if maybe the alternator I put in is the problem?

Yes, the alternator is connected to the starter motor, to the same
terminal as the big red wire from the battery. So the alternator is
live all the time. Who knows if you've fried something by connecting
the ground wire to the wrong place.

Signature

Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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richardson.randall@gmail.com - 28 Jul 2006 21:49 GMT

It turns out that the ground wire wasn't firmly attached to the
chassis. I located the other end (hidden under the oil filter) and I
saw that it was loose. Once I tightened it there was no longer a charge
on the alternator case, and the only place that had a 12 V charge when
the car was off was the battery terminal. Everything works fine now.

Thanks for your help.
-Randall

> > Mike,
> > Thanks for your reply. As far as the entire alternator being charged
[quoted text clipped - 12 lines]
> Replace tt with t (twice!) and remove parentheses to email me directly.
> (But I check the newsgroup more often than this email address.)

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