How do you test camshaft position sensor for a 91 560SEL?

[emmydotnet]

Is there a way to test (Resistance or voltage) to verify that the camshaft position sensor is working properly? i am trying to rule it out as the cause of a rough idling at start up. I did clean the sensor and traced back the wiring to the test port ( i believe the X1 test port). However, the wires from the senor is just terminated to the test port without any connection to anything. what am I missing?