YANMAR OIL PRESSURE SENDER

Does anyone know how the oil pressure sender works to drive the oil
pressure gauge?

While motor sailing a day or so ago we watched the oil pressure gauge
flicker from normal to 0 psig. You can imagine the circumstances when
this happened. We were one mile from entering the North Bar passage,
connecting the Atlantic and the Sea of Abaco. Seas were not breaking
in the passage, but swells were six to eight feet, and we were surfing
some. After stopping the engine we realized the oil pressure alarm
did not beep until the engine stopped. That was the good news. After
careful inspection we started the engine again. The alarm silenced.
Oil pressure read low on the gauge. The gauge continued to flicker.
Engine temperature and all else were normal. We motored on.

The oil pressure sender has one small black wire connected to it.
When engine is running there is 12 volts or more at the connection.
The oil pressure gauge reads 0 psig. Grounding the connection causes
the gauge to read 80 psig. I have to believe the sender has failed.

Craig.
Charmed IP 440.33