Distributors & Ignition Systems - LUCAS Constant Energy Ignition: Operation

As the distributor shaft turns, the reluctor turns with it. See Fig 1. As each of the 6 or 12 teeth approach and pass the pick-up coil's pole piece, the strength of the magnetic field around it will vary. This creates a voltage in the winding of the pick-up coil.

Fig 1: Exploded View of Lucas XJ6 Distributor for Constant Energy Ignition System

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

For exploded view of XJS distributor, see Figure.

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.