Ignition System - Electronic: Operation
As the distributor shaft turns, the reluctor turns with it. See Fig 1. As each of the 6 teeth pass across the pick-up coil's pole piece, the magnetic field strength around the pick-up winding is intensified. This creates a voltage in the winding of the pick-up coil.
The rise and fall of this voltage is sensed by the amplifier module, which then sends a signal, cutting off voltage to the primary circuit of the ignition coil. This causes a voltage surge in the secondary, firing the spark plugs at the proper time.