Ignition System: Description and Operation

Ignition System Circuit Diagram:

IGNITION SYSTEM GENERAL DESCRIPTION
The ignition system used for this vehicle has an Electronic Spark Advance (ESA) system and consists of the following parts:

^ Engine Control Module (ECM) - It detects the engine condition through the signals from the sensors, determines the most suitable ignition timing and time for electricity to flow through the primary coil and sends a signal to the igniter.
^ Igniter (power unit) - It turns "ON" and "OFF" the primary current of the ignition coil according to the signal from ECM.
^ Ignition coil - When the ignition coil primary current is turned "OFF," a high voltage is induced in the secondary winding.
^ Distributor - It distributes a high voltage current to each plug.
^ Secondary (spark plug) wires and spark plugs.
^ Camshaft Position (CMP) sensor - Located in the distributor, it converts the crank angle into voltage variation and sends it to the ECM.

IGNITION TIMING PARAMETERS
In ESA system, the ECM is programmed for the best ignition timing under every engine condition. Receiving signals which indicate the engine condition from the sensors such as engine revolution, intake air volume, engine coolant temperature, etc., it selects the most suitable ignition timing from its memory and operates the igniter; thus ignition timing is controlled to yield the best engine performance.