Date: Wed, 21 May 2003 20:19:18 -0700
Reply-To: mark drillock <drillock@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <drillock@EARTHLINK.NET>
Subject: Re: Oil Light / Buzzer despite NORMAL pressure
Content-Type: text/plain; charset=us-ascii
VW did a smart thing with the 2.1 engine oil pressure system. It uses 2
switches and monitors one at low rpm and the other at high rpm. The low
rpm switch work normally, namely reads as grounded when the pressure is
too low, but open when the pressure is good. The smart thing they did
was make the high rpm switch works in the opposite fashion. It shows as
open when the pressure is too low and ground when the pressure is good.
This means that if the switches should become disconnected for some
reason the oil pressure warning will sound when the engine rpm gets
above about 2000. This prevents you from driving around with low
pressure while thinking things are fine because the light is not on. If
the high rpm switch is not connected the light and alarm will be
triggered above 2000 rpm.
You can't just leave the high rpm switch unplugged. If there is not a
good connection between it and the oil pressure circuit board inside the
speedo then the alarm will sound.
Mark
"Benjamin E. Beasley" wrote:
>
> I'm really hoping y'all can assist me with this one,
>
> Last winter, my '87 Synro had the nasty habit of flashing the oil light /
> buzzer when the tach hit about 2200 rpm and the engine was cold. No
> problem, I would just let the engine warm up a little and then go with no
> subsequent arousal of the oil light. Just to be thorough, I replaced the
> rear oil pressure switch, the one behind the belts and all of a sudden, the
> oil light / buzzer came on immediately after starting the car and stayed on.
> This happened in the middle of my recent trip to Arizona so I rigged a test
> light to that rear oil pressure switch (light on when key on, goes out when
> engine cranks) and hung it from the A/C condenser housing so I could see it
> in the rear view. Then I destroyed the little clapper in the instrument
> panel that allows the light/buzzer to do it's thing. Now, the system was
> almost perfect but failed to account for the front oil pressure switch
> (plus, was afraid it would come on during daytime and I wouldn't pick up on
> it) so I replaced the entire instrument panel with a better used one
> (odometer wasn't working either). After hooking everything up EXCEPT the
> oil pressure wiring in the engine bay, the light/buzzer come on right after
> starting the vanagon. My question is, with no signal coming forward from
> the engine bay does the circuit know that something is awry and sound the
> alarm? Should I disconnect my test light and go through the acrobatics of
> reconnecting the rear oil pressure switch (mirror on a stick and 90 degree
> pliers)? Or does this mean that my new oil pressure switch is faulty as
> well? Any thoughts of other stuff to check? I should mention that I've
> tested the front oil pressure switch and it is not to blame.
>
> Ben Beasley
> 1987 Syncro Vanagon GL "Babe, the Big Blue Ox"
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