The ignition system consists of the following components and wiring circuits:

The distributor ignition (DI) wiring circuits between the CKP and PCM use the following service common names:

The DI wiring circuits between the CMP and PCM use the following service common names:

The DI wiring circuits between the PCM, IC module, and coil use the following service common names:

The IC module and the ignition coil both receive fused power on the ignition 1 voltage circuit. The IC module is also supplied an independent ground connection.

The DI system is responsible for producing and controlling a high energy secondary spark. This spark is used to ignite the compressed air/fuel mixture at precisely the correct time to provide optimal performance, fuel economy, and control of exhaust emissions.

This electronic ignition system is known as a high voltage switch (HVS) distributor ignition system. Trigger information is supplied only by the CKP sensor. The CMP HVS is located inside the distributor, and is used for fuel injector sequencing and misfire diagnosis. There is no back-up or by-pass system used, so the engine will not run without a valid CKP input. The PCM signals the coil to fire through the IC module. The resulting secondary energy is distributed to the spark plugs by a conventional distributor cap and rotor assembly.

The following is a description of ignition system components and their functions.

The CKP sensor is located in the engine front cover perpendicular to a reluctor ring mounted on the crankshaft nose. The reluctor ring has 3 or 4 slots depending on whether the engine has 6 or 8 cylinders. As the reluctor rotates past the sensor tip, the slots change the sensor magnetic field to produce a voltage ON-OFF signal. Based on these signals, the PCM is able to determine crankshaft speed and position.

The CMP sensor is located in the distributor base. The distributor is driven by the camshaft and distributes the secondary voltage to the spark plugs through the distributor rotor, cap, and wires. The CMP sensor produces a signal once every revolution of the camshaft. The CMP signal identifies the position of the #1 cylinder relative to the crankshaft.

The ignition coil provides the necessary secondary energy to produce a strong enough spark at the plugs. The coil is triggered by the IC module which in turn is commanded by the PCM. There is no back-up or by-pass function in the IC module.

The PCM is responsible for maintaining proper spark and fuel injection timing for all driving conditions. Ignition control (IC) spark timing is the method the PCM uses to control spark advance and ignition dwell. To provide optimum driveability and emissions, the PCM monitors input signals from the following components in calculating IC spark timing:

There is one circuit between the PCM and the IC module. This circuit is called the ignition timing signal and is by the PCM to command the IC module to trigger the coil.

There is only one mode of operation in this ignition system. The PCM sends timing signals to the IC module. The IC module will then amplify and send a signal to the ignition coil which will produce high voltage secondary energy. This high tension voltage will then be distributed through the coil high tension wire, distributor rotor, cap, and plug wires. Since the distributor has no influence on the base timing, adjusting the distributor will not change the base timing. However, the distributor on V8 applications can be adjusted to eliminate the chance of crossfire at the distributor wire terminals. Distributor terminal crossfire may cause poor performance. The V6 engine applications do not use an adjustable distributor.