Ignition Control Module: Description and Operation

Operation of Power Transistor (SOHC)

Turn ignition switch to ON position and battery voltage will be applied to primary winding of ignition coil.

When crankshaft position sensor signal is input to engine control module, ON-OFF control of ignition power transistor is performed by engine control module.

When ignition power transistor is turned on, current flows from ignition coil (primary winding) to ground through igition power transistor.

When ignition power transistor is turned off, high voltage is generated in primary winding of igniton coil which induces even higher voltage in the secondary winding causing a spark at the spark plug.