Ignition System: Description and Operation

When the ignition switch in ON or START , battery voltage is applied to the ignition coils. As the crankshaft turns, the engine control module (ECM) receives the signals of CKP and CMP sensor. Based on these inputs and other engine sensors, the engine control module (ECM) controls the current through the ignition coil by turning the power transistor (built-in ECM) on and off.

When current flow through the primary winding is stopped(turn the power transistor off), a high voltage is induced in the secondary winding of the ignition coil. The high voltage is applied to the two spark plugs that are connected in series.