Auto-check unit voltage warning

["Marcus Oxer" <mdoxer@globalnet.co.uk>]

Dear List,

I now have some more information about a problem I posted previously - I
wonder if anyone can help me? The "voltage too low/too high" warning has
been displaying on the auto-check/multi-check system on the dash of my 1990
Audi Coupe 2.3E. It comes on about 20 seconds after switching on the
ignition, and then remains on for the whole of my journey. I had one
suggestion that it may be the alternator brushes starting to go... However,
I sometimes see this warning even when the engine is not running (with the
ignition on).

I had an Audi dealer take a look at the problem today - they spent 2 hours
vainly trying to find a fault (although fortunately only charged me 1
hour's labour!). They confirmed that alternator output and battery voltage
are both OK, and that the auto-check unit and its wiring/connections are
OK. Their next suggestion is that I should have a "full wiring check using
VAG 1598". This sounds like it's going to use an Audi diagnostic tool? Does
anyone know of any checks I can do myself before I spend more hard-earned
on this problem?!

Any suggestions would be gratefully received!

Regards

Marcus Oxer

mdoxer@globalnet.co.uk