Distributor Ignition (DI) System
The distributor ignition (DI) system includes the following components:^ The distributor
^ A hall-effect switch
^ The ignition coil
^ Secondary wires
^ Spark plugs
^ Knock sensor
^ A crankshaft position (CKP) sensor
Distributor:
The vehicle control module (VCM) controls the ignition system. The VCM performs the following functions:
^ Monitors information from various engine sensors
^ Computes the desired spark timing
^ Controls the dwell and firing of the ignition coil (through an ignition control line to the coil driver)
The distributor connects the ignition coil and spark plugs through secondary wires. The rotor directs the spark to the appropriate cylinder. The distributor has a hall-effect switch that connects to the VCM through the primary engine harness. This switch provides cylinder identification information.
Identification
The part number is pin stamped into the plastic base, directly below the high tension terminals and next to the three pin camshaft sensor connection.
Ignition Coil
When signaled by the VCM, the coil driver controls the current flow in the primary winding of the ignition coil. The primary engine harness makes the interconnects. The ignition coil can generate up to 35,000 volts and connects to the distributor through a secondary wire.
Secondary Wires
The secondary wires carry voltage between the ignition coil, the distributor, and the spark plugs. The secondary wire connections form a tight seal that prevents voltage arcing.
Hall-Effect Switch
The hall-effect switch connects to the VCM through the primary engine harness. The hall-effect switch provides cylinder identification information. The hall-effect switch is under the distributor cap.
Crankshaft Position Sensor
The crankshaft position (CKP) sensor connects to the VCM through the primary engine harness. The crankshaft position sensor provides crankshaft reference information to the VCM for spark and fuel delivery. The crankshaft position sensor is in the front cover behind the crankshaft balancer.
Ignition Base Timing
NOTE: The distributor used with the OBD II ignition system is located in a fixed, non-adjustable position. Do not adjust the engine base timing by rotating this distributor. Otherwise, crossfiring and damage to the distributor will result.