How do I test my oil pressure sender?

[v8nut]

I am not seeing any oil pressure on the gauge on my 35 Phaeton. I don't think the oil pressure is zero. I assume the sender is a variable resistor and the gauge is an ammeter. I have a multimeter to measure the resistance. What readings should I expect? Or, should I test the gauge unit first? If so, how? Any advise would be appreciated. Jim in San Jose.