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Re: [T3] Battery went flat while driving


On 10 Oct 2003 at 22:25, Andrew Davidson wrote:

> Jim Adney:

> >Question to get you started: When you turn the key ON, do the idiot lights
> >come
> >on? If they do, do they go out when you turn the key to START?
> 
> The idiot lights do come on when i turn to ON and go off when i turn to
> start although i seem to recall a persisting feint glow at night but you
> can't notice it during the day. BTW, now the engine is stone cold and its a
> cold morning and the engine does not turn at all, but there is a click
> coming from there.

Okay, the fact that the idiot lights do this means that the voltage is getting 
sucked down to "nothing" by the starter or the solenoid. Your job is to figure 
out what the cause is. Get a friend and a voltmeter. The click that you hear is 
probably the solenoid trying to turn on the starter, but if this is a FI car, 
there may also be some relay clicks that are unrelated.  

Measure the voltage from battery POST to battery POST. If THIS voltage drops 
below 8V when the key is in START then the battery is dead. If not, the voltage 
drop is elsewhere.  

Move your probes outwards, negative to the body of the car, + to the + battery 
CLAMP. Repeat the test. Once you find a measurement where the voltage drops 
with the key in START, you know that you're spanning the problem area. You can 
then use the voltmeter to check for voltage drops across things that should be 
as the same voltage: battery post to clamp, battery cable to starter, etc.  

Once you find the connection that has the voltage drop, take it apart, clean it 
out, grease it, put it back together, and repeat the test.  

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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