Oil pressure light above 1600rpm

[rikiraph]

I'm new to this forum and thought I would post it for ideas experience. It can't really be a mechanical fault it's a bit of a curly one but I don't really know how the logic of the circuit works.
I have a 2006 2.5 TDI BNZ transporter. Engine seems to be running perfectly but every time it reaches 1600 RPM or about that the oil light beeps and flashes sometimes it turns off when it drops below 1600rpm sometimes it stays on.
I have removed the oil pressure switch and installed a pressure test gauge in there and the pressure is running perfectly all the time when hot and cold. However even without the pressure switch installed exactly the same problem occurs. So maybe this is the open circuit fault? I have no idea why it would only happen above 1600 RPM. Does anyone know the logic of the circuit? I'm guessing time to go to VW specialist because they will know exactly which terminals to check continuity etc

[Guest001]

IS oil topped up???

[rikiraph]

Hi yes oil light comes on even with no switch installed

[LogicprObe]

I know little about BNZ engines but I do recall reading that some cars have two oil pressure sensors.
(it may not even have been a VW)

[h100vw]

Lots of early VWs have 2 switches, a low [pressure one that turns the oil light off and a high pressure one that turns it on, in conjunction with the instruments.
So if the clock dont get the 1.8bar signal at around 2000 revs,( could be lower on a diesel) then the buzzer comes on.
Disconnecting the switches will cause this buzz for sure.
Check the oil pressure is within spec above 1600 revs
Then replace the appropriate switch if it is.

[syncro]

Common problem. High pressure switch is stuffed or the incorrect type fitted or open circuit in the wiring.

[h100vw]

And make sure you fit the switches and connect them correctly. Note the colours of the wires and the pressures written on the side of the switches