Ignition System - DURA-Spark II: Operation: Notes
An armature on distributor shaft rotates past stator (pick-up coil). This armature has the same number of teeth as the engine has cylinders. A signal is sent to control module as armature teeth rotate past pick-up coil.
The module determines when to turn current to coil primary windings on, and off. This current collapse in the primary causes a high voltage surge in the secondary windings. High voltage is routed to the spark plugs through rotor, distributor cap and spark plug wires.