Ignition Control (IC) System

Ignition Control Wiring Diagram:

Purpose:
The electronic ignition system controls fuel combustion by providing a spark to ignite the compressed air/fuel mixture at the correct time. To provide optimum engine performance, fuel economy, and control of exhaust emissions, the ECM controls spark advance of the ignition system.

Operation:
The ignition system consists of three ignition coils, and ignition control module, a dual hall effect crankshaft position sensor, and engine crankshaft balancer with interrupter rings attached to the rear, related connecting wires, and the Ignition Control (IC) and fuel metering portion of the ECM.

In this ignition system, neither end of the secondary winding is grounded. Instead, each end of a coil's secondary winding is attached to a spark plug. Each cylinder is paired with an opposite cylinder (1-4, 2-5, 3-6).

These two plugs are on "companion" cylinders, i.e., on top dead center at the same time. When the coil discharges, both plugs fire at the same time to complete the series circuit. The cylinder on compression is said to be the "event" cylinder and the one on exhaust is the "waste" cylinder.

The cylinder on the exhaust stroke requires very little of the available energy to fire the spark plug. The remaining energy will be used as required by the cylinder on compression stroke. The same process is repeated when the cylinders reverse roles. This method of ignition is called a "waste spark" ignition system.