Followup: Oil light flashing/buzzer sounding in 1985 4000SQ - FIXED

[John <jb@access.digex.net>]

This is a follow-up concerning my oil buzzer/light problem:

After locating the two oil pressure switches (thanks Mike Tipton
for telling me exactly where they are on my car!), I found that both of
them had green oxidized contacts.  Merely cleaning them with a spray
electrictrical contact cleaner stopped the warning buzzer, and also
fixed the .3 bar dummy light.

The oil light hadn't been lighting up when I turned the ignition
part way - there must be a contact through the .3 bar switch at this
point to light up the oil light; once the engine is started, it goes
out (once the oil pressure goes over .3 bar).  Basic stuff to most
of you - but I hadn't noticed the light not going on.  Guess I should
pay more attention to make sure all my warning lights are functioning.

After a couple of days driving, the buzzer went off again, but
pulling the 1.8 bar switch connector off and putting it on caused
enough abrasion to fix the contact again.  I have now replaced that
switch, and cleaned the plug contact out with sandpaper, and have not
had a warning in several days.  (I am also now assured that the
switch isn't stuck closed.)

Thanks to everyone who replied.  I had no idea how the oil pressure
system worked at all, and even though the fix was simple, I couldn't
have done anything without the explanations from Phil, Sam Letzring,
etc.

John
jb@digex.net
1985 4000S Quattro