Long time lurker, slow learner.

[bradyzq]

Yup, the first two docs show a vr cam sensor. They even show the waveform to remove any doubt. But all the Bosch cam sensors I've seen have been Hall, as mentioned in the last doc.

Can you just test it? Voltmeter, or ideally a scope, connected across the 2 pins of the sensor. Then wave a piece of steel past the sensor tip. If A voltage is generated iit's vr. If not, the sensor is a hall, or its broken.

[billr]

"A two wire Hall effect THEORY from another forum - has anyone heard of such a thing?"

I don't know about automotive ones, but they are certainly available for industrial applications.

[Matt Cramer]

A two wire Hall effect sensor would most likely be using the body as the third (ground) wire.

[billr]

No, they don't use the case as a "third wire", they are true 2-wire. Kind of like a current-loop system. I'll look for info, I think Allegro makes some chips and Turck the assemblies.

[billr]

The Allegro A1244 is a 2-wire Hall device. (Note that it has three leads, but one is "NC")