[Vwdiesel] Electrical problem

[Terry Briggs]

Save yourself some time and just go have the battery load tested, that 
will at least tell you the condition f the battery. I suspect the only 
thing that could drain the battery that fast would be the glow plugs, 
not much else would have the required draw to kill the battery that 
quickly and completely.
On Apr 2, 2009, at 8:11 PM, Erik Lane wrote:

> Today my wife got stranded at a voice lesson with our 81 jetta diesel. 
> She
> got in the car to leave after having been there for 90 minutes and 
> when she
> turned the key nothing happened. When I got there to tow it home I 
> figured
> it might be a bad connection somewhere and I would be able to use 
> jumper
> wires to at least crank the starter, but there was nothing. When I put 
> a
> meter on the battery all I got was 0.35V!!
>
> The clock stopped 30 minutes after she got there, so something managed 
> to
> completely drain a relatively new 900CCA battery in roughly 30 
> minutes. None
> of my fuses are blown, either.
>
> Seems to me that nothing would be able to drain it that fast without 
> popping
> a fuse if it was a fused circuit. The only unfused circuits that I can 
> think
> of are the starter, glow plugs, and the alternator. When I have the 
> battery
> cables disconnected I get a reading of open circuit - so there's not an
> obvious short. I thought maybe the alternator has a bad spot and it 
> moved a
> bit in all the work I did towing it home and getting it on and off the 
> tow
> dolly. But I took the drive belt off and turned it slowly by hand while
> watching an analog meter on the ohms setting, and the needle never so 
> much
> as wavered. I checked the meter to make sure the battery in it was 
> good, and
> if I turned on a light switch in the car the needle swung full field to
> zero.
>
> So I'm left with the conclusion that either it's a strange intermittent
> problem, or it's the battery, or possibly checking the alternator like 
> that
> is not very conclusive. I have the battery on a small 6 amp charger 
> right
> now, and it's been on that charger for a couple hours, but it's still
> drawing the full 6 amps. If it stays like that for very long then I'm 
> going
> to start suspecting the battery of being bad, but like I said it's
> relatively new, still under full warranty. So I would be glad if 
> that's all
> the problem was, but I would also be surprised.
>
> Can anyone see something obvious that I'm missing? I need this car to 
> be
> reliable, so I don't want to just put it back together without having 
> found
> what did this in the first place and fixing the problem. Is there a 
> better
> way of checking for an internal short in the alternator? It's also 
> only a
> couple years old, but it seems to work fine. In fact the car has been 
> very
> good and absolutely reliable for us for many years up to this.
>
> Thanks in advance!
> Erik
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