Re: One dead Audi. Any clues?

["Matt Rooke" <mrooke@fcpa.fujitsu.com>]

<snip>
>So- the problem: car starts instantly and idles beautifully when
>jump-started, displays 'OK' and 'ABS off' on the autocheck occasionally
>when driving, dead after shutting the ignition off.

I've BTDT a couple times:
- corroded battery connectors
- dead dead battery
but could also be alternator, ie, battery has enough juice to run things but not
enough to start engine.  Actually, your funny displays tend towards this diagnosis.

procedure:  use your most excellent multimeter to check the battery voltage while
car is off.  If much less than 12V, then it has no charge.  This could be because
it is dead, or because it hasn't been charging due to corroded connections.
Try cleaning the connectors and jumping the car or charging the battery overnite.
Measure voltage while running, it should be 13.5 +/- indicating that the alternator
is healty.
If while off the voltage is close to 12V, try starting it. If (after having been charged)
the act of trying to start takes the voltage from 12 down to something less than 10, battery is dead.
Make sure all the connections are clean and solid before concluding either the battery
or alternator is the problem, its much cheaper!

Hope this makes some sense!

Matt Rooke
'91cq