Date: Sat, 5 Apr 2008 12:51:43 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Oil Pressure Light on-need help! (dealer cant fix it)
In-Reply-To: <9f4608e90804050913g139fa0d0wf8b1ee984b1c86c9@mail.gmail.com>
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What is a bit scary is that this "Dynamic Oil Pressure Warning System" is
used on most all VW, Porsche, and Audi products starting on some as early
as '84. My guess is that it came about due to oil system failures due to
the over head cam engines having the valve guides suck out the oil or the
cam tunnel failures causing those engine to loose pressure. The board and
wiring is the same on most of these vehicles and the major difference is
the sensor ratings.
The light and buzzer sounding over 2,000 rpm or so is due to the higher
pressure switch not satisfying or completing the circuit to ground. On the
Water boxer, this is the switch near the oil pump or under the water pump.
This should be a .9 bar, (12.7 psi.) switch, color is grey. Note that this
switch location is before the oil filter so the only way that the brand of
filter will effect this switch operation would be for it to have a higher
flow resistance which really means less oil flow down stream.
The gauge voltage stabilizer in the instrument cluster has no effect or
impact on this circuit.
Usual buzzer causes are low oil pressure, Intermittent symptoms) faulty
pressure switch or wiring connection problem. The electrical part is easy
to diagnose if you know how to troubleshoot electrical circuits and use a
meter. Wire condition and the connectors are becoming a real problem as
our vans are aging. Low mileage does not mean that the 20 year old wiring
is good.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Al Knoll
Sent: Saturday, April 05, 2008 12:14 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Oil Pressure Light on-need help! (dealer cant fix it)
If we approach the situation as a symptom-cause situation, the symptom is
the OP light. The cause is unknown. There is a 3 pin voltage regulator
in
the instrument pod that may be on it's way out. However for a quick check
have the dealer troublshoot the sensor system, not the OP 'problem'. As a
very simple check make sure the wiring and contacts from the OP sensor to
the instrument pod are intact and secondarily, measure the sender itself.
Left as an excercise for the HQOPDT (highly qualified over paid dealer
technician) to figure out how to do that. The motor should have 20-50 oil
and an acceptable Mahle filter.
As a last resort temporarily exclude the VW measurement system by
attaching
a known good oil pressure guage and reading the values at 1200RPM and
3000RPM.
Actually I would do this first but then I have a VDO pressure guage and
perhaps the service establishment doesn't.
Sometimes just removing and reconnecting the wiring will make the symptom
vanish. A recent event at a well known shop caused considerable concern
when after some servicing, the check engine light came on periodically,
the
code thrown by the ECU (SVX motor) was non sticky and showed 'ignition
system fault' indicating that the measured voltage at the ignition switch
was out of spec. Removing and replacing the connectors to the switch
module
fixed it. The fault was indistinguishable by the ECU from an ignition
fault
as rightly it should be. However the ECU considers only it's measured
values, an open wire can give a false reading.
