[Vwdiesel] 89 Jetta na charging system

[Tad]

I had a similar experience years ago with my 78 Rabbit.

The battery light never really "came on", but sometimes, in the right light,
if you looked carefully you could see a dull red glow (much easier to see in
the dark of course).

Who knows how long it had been doing this before I noticed it, but when I
did notice it (on my way home from college for the weekend of course... with
a 5 hour drive through God-forsaken-BF-nowhere in between), I stopped into
one of those Battery Factory type places.

They put the load tester on the car, pulled a good load and pronounced the
alternator "fine".

I continued to tootle around all weekend, aware of the coming and going of
the light, but trusting the "professional" and assuming it was "fine".

My last night in town, the alternator finally gave up on the
"on-again-off-again" and just went with the off.  I was a good 30-40 minutes
from my folks house(where I was planning to sleep) but relatively close to
my buddy's place, so I headed there.  As I drove, I could see the headlight
(single - in a happy coincidence, one of them had burned out, saving
precious juice!) and dash lights getting dimmer and dimmer.  When I was
about a mile away, the car started to misfire at higher RPMs, I assume
because the electric fuel pump could no longer supply enough gas.

I ended up crashing at my buddy's house and changing the alternator in the
morning.. thankfully he had the deep socket necessary to get the alt pulley
off.

Long story short... it's a sign of impending failure.  Just change the
alternator before you end up stranded somewhere. :)

On Mon, Jul 25, 2011 at 3:42 PM, Doyt W. Echelberger <
doyt at buckeye-express.com> wrote:

>  When my car is running, is there EVER a time that the battery dash light
> should come on red, other than the brief interval when I first switch on the
> ignition ? (If this is a duplicate post, I apologize.)
>
> The red dash light for the battery on this 89 Jetta diesel has glowed dull
> red at times and not at other times. The dim red light on the dash called my
> attention to this by coming on during a drive around town recently. OK, red
> dash lights are put there for a reason by the designers so I popped the hood
> and with the engine running put the volt meter across the battery posts. It
> read a steady 12.8 volts.
>
> Conclusion: The alternator wasn't charging the battery at that time, and
> 12.8 volts didn't trigger the voltage regulator to fire up the alternator
> fields.
>
> So, I made an appointment to have the charging system checked. I take the
> car in tomorrow.
>
> This morning, I started the engine and there was NO RED BATTERY LIGHT
> flickering on the dash. I popped the hood and put the voltmeter across the
> battery terminals and read 14.8 volts.  I turned off the engine and the same
> voltmeter read 12.8 volts. Clearly, the alternator has started working.
>
> I then drove the car for half an hour. The battery light stayed off,  off
> at the end of the trip I again measured the voltage across the battery
> terminals while the car was running.  13.7 volts.
>
> I am puzzled by this behavior.  Will my mechanic be able to identify the
> cause of this unreliable feature and fix it?
> I have a spare alternator from my old 1985 Jetta TD, and it worked OK a few
> years ago when the TD was running.
> I think I'll put it in the trunk when I take the car in, and mention it to
> the mechanic.
>
> But right now, he doesn't have anything to fix. The alternator seems to
> work just fine. Does he have miracle tools that tell him what made my
> battery light come on one day, and then stay off the next?
>
> Doyt
>
>
>
>
>
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