Ignition System: Description and Operation

PURPOSE
The Engine Control Module (ECM) is programmed with data for optimum ignition timing under all operating conditions. Using data provided by sensors which monitor various engine functions (RPM, intake air volume, engine coolant temperature, etc.), the ECM triggers the spark at precisely the right instant.

OPERATION
The ECM monitors the engine condition by signals from each sensor, calculates the ignition timing and sends an ignition signal to the Power Transistor. High voltage from the ignition is distributed to each Spark Plug in the appropriate order to generate a spark between the electrodes, which ignites the air-fuel mixture.

Power Transistor
The Power Transistor temporarily interrupts the primary current in the Ignition Coil which generates sparks at the Spark Plug.

Ignition Coil
The Ignition Coil uses a closed core coil with the primary coil wrapped around the core and the secondary coil wrapped around the primary coil. This allows the generation of a high voltage sufficient to cause a spark to jump across the Spark Plug gap.

Distributor
This correctly distributes high voltage to the Spark Plug of each cylinder in the specified ignition order. The Distributor also houses the Ignition Unit (Optical Pickup Assembly).