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

[Hillbilly]

IS oil topped up???

[rikiraph]

Hi yes oil light comes on even with no switch installed