Ignition System: Description and Operation

GENERAL INFORMATION
Interruption of the primary current flowing in the primary side of the ignition coil generates high voltage in the secondary side of the ignition coil. The high voltage thus generated is directed by the distributor to the applicable spark plug. The engine firing order is 1-3-4-2 cylinders.

On application of high voltage, the spark plug generates a spark to ignite the compressed air fuel mixture in the combustion chamber.

The engine control module (ECM) /powertrain control module (PCM) makes and breaks the primary current of the ignition coil to regulate the ignition timing.

The ECM/PCM detects the crankshaft position by the crankshaft position sensor installed at the front end of the crankshaft to provide ignition at the most appropriate timing for the engine operating condition.

When the engine is cold, the ignition timing is slightly advanced to provide optimum performance to the operating condition.

System Diagram:

OPERATION
- Turn ignition switch to "ON" position, and battery positive voltage will be applied to primary winding of ignition coil (incorporated into the distributor).
- When the crankshaft position sensor signal is input to engine control module (ECM) /powertrain control module (PCM) , ON-OFF control of ignition power transistor is performed by ECM/PCM.
- When ignition power transistor is turned on, current flows from the ignition coil (primary winding) to ground through the ignition power transistor.
- When the ignition power transistor is turned off, high voltage is generated in the primary winding of ignition coil which induces even higher voltage in the secondary winding, causing a spark at the spark plug(s).