I would see if anyone you know has a oil pressure tester, remove the factory one and screw in the tester (the one we have at work is just an analog gauge with hose to go in where sender goes, run it and see if oil pressure is correct for your engine. My landcruiser has factory oil pressure gauge and was showing pretty much no oil pressure at idle but checked with gauge and has a fault somewhere not worried about it really because I know the pressure is fine.
But I would say it is an electrical problem.