Ignition System: Description and Operation

With the ignition switch in the ON or START position, battery voltage is applied to the ignition coil in the distributor assembly. As the distributor shaft turns, the Engine or Power Control Module (ECM) or (PCM) receives the crankshaft position sensor inputs from the distributor. Based on these inputs and other engine sensors, the PCM sends a signal to the ignition control module. The module grounds the primary winding of the ignition coil. When the current flow through the primary winding is stopped, a higher voltage current is induced in the secondary winding of the ignition coil; the high voltage current then flows through the distributor cap & rotor to the proper spark plug.

A signal is also sent from the ignition coil to the instrument cluster to operate the tachometer.