Ignition Coil: Procedure: Description

The ignition coil is a small transformer that transforms the battery voltage to 30 kV or more to create a spark in the spark plug gap in the cylinder.
The igniter built into the ignition coil includes the power transistor and it is an electronic switch whose electric current is controlled by the Engine Control Module (ECM) signal.
The ignition timing is controlled by the ECM and the standard ignition timing data according to engine operating conditions is stored in the ECM memory.
The engine operating conditions (speed, load, warm-up state, etc.) are detected by the various sensors. Furthermore, this is based on these sensor signals and the ignition timing data, when the ECM applies the ignition signal to the ignition coil for a certain period of time, igniter is energized and current flows and rises gradually to the primary coil and the magnetic field is produced.
When the current in the primary coil is cut off by the ignition signal of the ECM, the rapid change of the magnetic flux by the mutual induction action is induced to the secondary coil and high voltage is generated depending on the coil winding ratio.
This high voltage generated from the secondary coil is caught in the spark plug gap and discharges as the electric field is destroyed to generate a spark.