Ignition System: Description and Operation

PURPOSE
The ignition system provides spark control to the engine during all modes of engine operation. The system consists of 3 sub-systems: primary ignition, secondary ignition, and timing control.

CONSTRUCTION
The system uses a separate Ignition Control Module (ICM) and coil.

OPERATION
Primary Ignition Components
These components include coil primary circuit, ignition control module, and ignition switch. When the ignition is switched "ON," it charges the primary coil windings. When the engine is running, the ICM induces the spark by grounding/ungrounding the coil primary circuit negative side.

Secondary Ignition Components
These components include spark plugs and wires, distributor cap, rotor, and coil secondary circuit. When the ICM grounds the primary circuit, an inductive charge builds up in the secondary circuit. When the ICM ungrounds the primary circuit, the inductive charge collapses and sends spark from the coil to the distributor. The rotor and cap then direct spark to each spark plug.

Advance Components
Advance and retard functions are controlled by the Powertrain Control Module (PCM) . The PCM receives signals from various switches and sensors and determines when to send the spark timing signal to the ICM.