Actual oil pressure is good. Wade said it could be a grounding issue with the gauge. Where would the ground wire be? Any thoughts? Sent from my iPhone using FerrariChat.com mobile app
A gauge earth or sender earth? Regarding the sender, it's a (combined) oil pressure/low pressure sender and it uses its case as an earth. When the sender is screwed into the engine block, the engine block and its earth strap/s become the return path. If you can find your sender/transmitter, with the ignition turned on, try pulling the plug off the sender and see if the gauge responds. If not, with the ignition turned on, try momentarily shorting each pin on the sender wiring harness to earth. There are two pins. Either your warning light will come on or your gauge will respond. I could give you the wire colours, but the colours on your car have probably faded.
Just looking at the diagrams, it won't be a gauge earth. It doesn't have one. The car provides a voltage to the gauge. The sender provides an earth. It shouldn't be a voltage problem unless your water temperature is also not working. For what it is worth, the applicable wire colour on your sender should be grey with a black tracer. The terminals on the oil pressure sender are particularly fragile. Check to see if one hasn't broken off. If you need to install a new one, be very careful not to apply too much force to the nuts.
Image Unavailable, Please Login The oil pressure sender is located just under the oil filter. There may be markings on the unit (G is for the gauge, WK is for the oil pressure warning light) Here's the wiring diagram for a 5.2 car: 5.2 Instruments Wiring Diagram
