Ignition System - DURA-Spark III: Operation

Fig 1: Wiring Schematic of Dura-Spark III Ignition System

With the ignition switch turned on, the primary circuit is on and the ignition coil is energized. See Fig 1. The EEC system (not the distributor as in Dura-Spark II systems) provides a signal telling the ignition module to turn off the coil primary circuit.

The length of time the primary circuit is turned on or off is controlled by the EEC Electronic Control Assembly (ECA). See Fig 2. When the current is on, it flows from the battery through the ignition switch, primary windings of ignition coil, and ignition module circuits to ground.

Fig 2: EEC III Electronic Control Assembly Located on left front inner fender well.

When current is turned off, the magnetic field which is built up in the ignition coil collapses, inducing high voltage to the secondary windings of the coil. This high voltage, produced each time the magnetic field builds and collapses, is transmitted by the coil to the distributor cap, rotor and to individual spark plugs.