Ignition System
When the external teeth on the timing core approach, align with, and pass the internal teeth on pole piece, an alternating current is induced in the pick-up coil windings. In the cranking mode, this alternating current signals switching transistors in the HEI module to make or break the ignition coil primary ground circuit. Once engine has started ECM takes control of primary ground circuit (EST mode).
When the primary ground circuit is removed, the magnetic field created by the flow of current in the primary windings collapses across the primary and secondary windings of the coil. This induces a high-voltage surge in the secondary windings of the coil. Secondary voltage is then discharged to the rotor which distributes it to the appropriate spark plug terminal. The distributor module may have either a 7-terminal ignition module, or an 8-terminal ignition module (sealed connector module), depending on application.