Circuit Description

Circuit Description
As the crankshaft turns, the engine control module (ECM) receives the signals from the CKP and CMP sensors. Based on these signals from the ECM controls the engine control relay coil and and then battery voltage is applied to the ignition coils through the engine control relay contact. The ECM controls the current through the ignition coil by turning the power transistor( built into the ECM) on and off.

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