Circuit Description

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

When current through the primary winding is stopped (at the moment the power transistor is turned 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 parallel.

The ignition failure sensor is connected between the ignition coil fuse and ignition coils to detect ignition failure.