System Description

PURPOSE
The ignition system ignites the air/fuel mixture in the combustion chamber at the proper time at all rpm levels and under all load conditions.

OPERATION
Primary Circuit
The primary circuit is the low voltage circuit. The primary circuit is the input circuit. Current flows through the following components at battery voltage:

Battery - Provides a source of electrical energy needed to start the engine.

Ignition Switch - Connects or disconnects the flow of electricity to the ignition system.

Primary Coil Windings - Converts the electrical energy into a strong magnetic field as long as the ignition switch is ON and the Powertrain Control Module (PCM) signals the Ignition Control Module (ICM).

Ignition Control Module - Receives data from a number of sensors and other electronic components. Based on data received and strategies programmed into the module's memory, the module generates output signals to control engine timing and advance.

Secondary Circuit
The secondary circuit is the high voltage or output circuit of the ignition system. The circuit may be required to deliver voltages as high as 40,000 volts.
Each of the following components has an important function for proper operation of this system:

Secondary Coil Windings - High voltages are induced into this section of the ignition coil. This is a result of the rapid collapse of magnetic field across the many thousand turns of relatively fine wire. The high voltage that is induced into the secondary windings will be available at the coil secondary tower for a short time.

Distributor Cap and Rotor - The surges of high voltage are delivered from the coil tower to the center terminal of the distributor cap by means of the coil high tension lead. These surges are then directed, one at a time, to each outer terminal of the distributor cap by the rotor, as the distributor shaft rotates.

Spark Plug Wires - These wires are connected between the outer terminals of the distributor cap and the spark plugs, and are arranged in order to follow the firing sequence of the engine.

Spark Plugs - The plugs provide a pre-determined gap within the combustion chamber so that each time a high voltage surge is delivered from the distributor, a spark will occur. If the proper mixture of fuel and air is present in the cylinder at the instant a spark bridges the plug gap, ignition and combustion will take place.