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. |
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