Without Electronic Spark Control (ESC)

Fig. 1 Chrysler electronic ignition system wiring:

This system, Fig. 1, is composed of a magnetic distributor, an electronic control unit, a wiring harness, a production coil and a single or dual ballast resistor.
The distributor is essentially the same as the conventional type except the contacts have been replaced by a pickup coil and the cam by a reluctor. With a conventional contact type system, the voltage necessary to fire the spark plugs is developed by interrupting the current flowing through the primary of the ignition coil by opening a set of contacts. With the Electronic System, the voltage is produced the same way, except that the current is interrupted by a transistor in the electronic control unit. This happens each time the control unit receives a ``timing'' pulse from the distributor magnetic pickup.
Since the magnetic pickup, reluctor and the control unit, which replace the contact points and cam, do not normally change or wear out with service, engine timing and dwell do not require periodic adjusting. This minimizes regular ignition maintenance of cleaning and replacing the spark plugs.