Ignition System: Description and Operation

This system uses a conventional type ignition distributor with the pulse transmitter mounted on the breaker plate and a trigger wheel (reluctor) mounted on the distributor shaft. The pulse transmitter consists of an induction coil attached to a carrier/pole piece assembly, which has the same number of elements (poles) as the engine has cylinders. As the distributor shaft rotates, the reluctor elements (also the same number as engine cylinders) pass by the pole piece elements, separated by a small air gap. As the reluctor elements pass through this air gap, alternating current is induced in the pulse transmitter coil. These voltage signals are transmitted to a separate ignition control module which uses the signals to control current switching in the primary ignition circuit. The module opens the primary circuit to induce secondary spark voltage in the ignition coil based on signals from the pulse transmitter and the TDC reference sensor, and alters coil saturation (dwell period) depending upon engine speed.