Oil Pressure Sending Unit Check
WARNING: This page is about a different car, the 1985 Nissan Maxima and 1985 Nissan 200SX. However, it is still accessible from the selected car via links, so may be relevant.
Remove harness connector at sending unit. Install ohmmeter probe between harness terminal and body ground. See Figure . When engine is stopped resistance should be more than 73 ohms. When engine is running (idling), reading should be less than 50 ohms. If any measurement is incorrect, replace sending unit.