NIPPONDENSO Electronic Ignition System: Operation

As the engine cranks, the distributor shaft turns, carrying with it the rotor shaft assembly. A reluctor (toothed wheel), mounted on the rotor shaft, turns inside a 2-pronged stator, which is attached to the magnet set.

As each reluctor tooth approaches and passes the stator upright prong, the magnetic field around the prong is broken. The pick-up coil and control module assembly is mounted inside the distributor, next to the magnet set and stator. Components are attached to the breaker plate assembly. See Figure.

The build-up and collapse of the magnetic field causes the pick-up coil to send a signal to the control module. The module, in response, opens and closes the ignition coil primary circuit. Each time this occurs, a voltage surge occurs in the coil secondary circuit, firing the spark plugs.

On California models, the computer monitors the ignition system along with other engine sensors. The computer then makes calculations and adjusts the air/fuel ratio.

No ballast resistors or resistance wires are used with the system.