The primary components of the distributor ignition (DI) system are:

The distributor is mounted directly to the front cover behind the water pump. The distributor directs the spark from the ignition coil to the proper spark plug secondary wire through a rotor. The spark plug secondary wire connectors in the cap are arranged in a way that eases in the routing of the spark plug wire harnesses. A cylinder number is molded on each distributor cap next to each spark plug secondary wire connector.

The distributor contains a signal disk and two optical camshaft position (CMP) sensors that send signals to the PCM for timing control. The PCM controls all ignition timing. Thus, there is no bypass mode built into the ICM. One CMP sensor senses 360 equally spaced slots in the signal disk in order to provide 720 signals per camshaft revolution for high resolution timing control. The second CMP sensor senses eight disk slots of varying lengths, providing a low resolution signal which tells the PCM which of the spark plugs is being fired.

The PCM determines if one of the timing inputs is not being received by comparing the two inputs. If the PCM detects one timing pulse without detecting the other, DTC 16 or 36 will set. Power for the optical CMP sensors, the system ground, and the two CMP sensor signals is transferred between the PCM and the distributor through a shielded harness on the four terminal distributor connector.

The reference signals toggle between 0-5 Volts as the camshaft turns. Therefore, any of the following situations can prevent the voltage from pulsing at the PCM:

1. An open circuit
2. A short to voltage
3. A short to ground
4. A defective sensor

The ignition coil and the ICM provide a spark to the distributor, timed by the PCM signals. Power for the ignition coil primary circuit and the ICM is supplied through the ignition switch. The PCM combines the CMP information supplied by the distributor with other system parameters. The PCM then calculates the required spark advance. The PCM signals the ICM, which turns on the primary circuit to the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When the primary circuit current flow stops, high voltage induced in the ignition coil secondary winding becomes the spark voltage for the spark plug. The spark voltage is delivered to the distributor through the secondary coil output wire, and then directed to the proper spark plug connector by the distributor rotor.

The electronic ignition (EI) system controls fuel combustion by providing a spark to ignite the compressed air/fuel mixture at the correct time. The powertrain control module (PCM) controls the distributor spark advance and retard (timing). The EI system provides improved engine performance, fuel economy, and control of exhaust emissions.

The EI system has the following advantages over a mechanical distributor system:

1. No moving parts
2. Low maintenance
3. Remote mounting capability
4. No mechanical load
5. More coil cool down time between firing events
6. No mechanical timing adjustments
7. Increased available ignition coil saturation time