Operation

^ Turn ignition switch to "ON" position, and battery positive voltage will be applied to primary winding of ignition coil.
^ When crankshaft position sensor signal is input to engine control module, engine control module makes ON-OFF control of ignition power transistor one by one.
^ When ignition power transistor is turned on, current flows from ignition coil (primary winding) to ground through ignition power transistor.
^ When ignition power transistor A is turned from ON to OFF, the spark plugs of No. 1 and No. 4 cylinders spark. Turning of ignition power transistor B from ON to OFF will produce sparking in spark plugs of No. 2 and No. 3 cylinders.