Sorry about the late reply. Haven't been getting all the update notifications.
The Hall sensor in the distributor is a magnet & Transistor pair that is triggered by a rotating metal shutter wheel (4 windows). When the transistor
is turned on, it grounds the wire (middle wire of plug connector) that goes to the ECM. When the ECM "sees" ground on that wire, it triggers the Ignition coil.
The hall sensor in this application is a square wave on/off signal. VW used either 12 or 5v operating voltages (outer two wires of plug connector).
Google or Youtube can explain better than I. :-)
Thomas
Saturday, November 3rd, 2012 AT 4:08 AM