[Vwdiesel] Cont'd Electrical gremlins - bad ground?

[Anton Largiader]

Oh man, I had this sort of thing on my Rabbit a year or so ago.  In my case
it was a bad alternator AND a bad battery.  The light would glow more and
more as the engine RPM increased.  The voltage would drop way down as soon
as I added loads like the lights, fan, etc.  I even swapped alternators (one
Motorola for another) and the problem stayed.  Getting a new/rebuilt Bosch
did the trick.

A loose belt will make the alt light glow.  We have had this on the 85 TD
over and over.  Reducing loads (like turning off the headlight, etc) can
make a difference in this case, too.

If you are charging the battery and then come out and it's 11.85 volts, your
battery is bad.  No question about it.  If it holds a charge after you plug
it in, but then is low after you have used the car, then obviously it's not
being charged by the car.

An easy way to monitor voltage is with a simple adapter plugged into the
cigarette lighter, leading to a voltmeter.  Only a buck or two to make it,
and it's one of the best things I've ever cobbled together.  Monitor the
voltage during an entire drive, to make sure it's charging at high RPM as
well as at low RPM.  And definitely clean up those connections.  Compare the
voltage at the lighter socket to the voltage across the battery itself.



==============================================
Anton Largiader, Chester Springs, PA
'94 K75RT, '93 R100GSPD,  '94 R1100RSA, '98 Jetta TDI
anton at largiader.com   http://largiader.com
==============================================
----- Original Message -----
From: "Brett" <dslfan at gwi.net>
To: <vwdiesel at vwfans.com>
Sent: Friday, November 08, 2002 7:24 AM
Subject: [Vwdiesel] Cont'd Electrical gremlins - bad ground?


> Hello,
>
> I'm writing this as I wait for my battery to charge outside, had to call
in
> late for work. I posted a while ago about electrical problems, looks like
> they are continuing. The problem is that my car is often losing the charge
> at the battery. Went out this morning and the battery is putting out about

> 11.85 volts, not quite enough to crank it with a long glow plug cycle (I'm
> in Southern Maine, it's cold enough all ready at 6:45 AM)
> I had my alternator rebuilt at a  local shop a few weeks ago, so I'm going
> to assume it's okay now. The alternator light has been lit up recently
when
> the engine speed goes up before I shift, then it goes off. I've been aware
> of the problem, but figured I'd ask you guys for advice. I was just
> searching the watercooled group, and saw a post from Loren in 2000 about a
> possible bad ground causing this. I don't think anything should be
actually
> draining the battery, especially since I don't even have a radio in my
car.
> The alternator is putting out the proper voltage when it's running (right
> around 13.9 volts). The battery is getting a proper charge when the car is
> running as well from my multimeter testing results. I had the battery
> tested and it is good according to the Autozone guy that tested it.
>
> How many electrical grounds are there on an A2 Jetta? I should probably
> clean them up. I recently replaced the starter -> positive battery
terminal
> cable with a low (2) gauge cable. I have a new 4 gauge cable to replace
the
> factory alternator -> starter cable. However, the battery ground cable is
> original and the location where it anchors to the body is a little
> corroded, all I've done is spray it with some Rust Check to try to keep it
> from getting worse. I'm suspecting it's just a really bad ground not
> allowing the battery to fully charge, but am not really sure. Any ideas?
> Thanks in advance.
>
> -Brett
>
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