Ignition Coil: Description and Operation

IGNITION COIL & POWER TRANSISTOR (BUILT INTO DISTRIBUTOR)
The ignition coil is a small molded type. The ignition signal from the Engine Control Module (ECM) is sent to the power transistor. The power transistor switches on and off the ignition coil primary circuit. As the primary circuit is turned on and off, proper high voltage is induced in the ignition coil secondary circuit.