I am working on a 1996 Nissan with a Crankshaft sensor problem but my question is not about that specifically, it is instead about sensor function. The Haynes repair manual (I know ) says the usual, test the circuit by checking the ground wire for proper grounding and for a reference voltage of about 5 volts. This thing has only two wires going to it, a black one and a white and assuming the black is ground that means the white should have the 5 volts on it. If I correctly understand the operation of most sensors I don't understand how one could use a "reference" voltage and only have two wires? How can a sensor function with only a ground wire and a reference voltage wire? What about the signal? This is a hall effect type sensor and I am wondering how such a sensor could supply any kind of signal if one wire is ground and the other is "hot" with no separate signal wire, is this possible or is this just another case of Haynes (or Chilton's for that matter) manual nonsense.