Distributor: Description and Operation

Distributor:

The distributor is mounted on the rear (flywheel end) of the cylinder head, and is direct-driven by the camshaft at one-half the crankshaft speed. Two offset drive tangs pinned to the distributor shaft engage with the camshaft in only one position. Rotation is counterclockwise as seen from the left of the vehicle.

The distributor houses the Camshaft Position (CMP) sensor, ignition coil, Ignition Control Module (ICM) and the distributor rotor. Within the distributor, the ignition coil transfers the secondary voltage to the distributor rotor. The distributor rotor transfers the voltage to each distributor to spark plug wire.

Hall Effect Device:

The distributor uses a Hall effect vane switch assembly, causing the ignition coil to be switched OFF and ON by the Powertrain Control Module (PCM) and ignition control module. The vane switch is an encapsulated package consisting of a Hall effect device on one side and a permanent magnet on the other side.

Rotary Vane Cup:

A rotary vane cup, made of ferrous metal, is used to trigger the signal OFF and ON.

Figure 7 - Magnetic Flux Field:

When the window of the vane cup is between the magnet and the Hall effect device, a magnetic flux field is completed from the magnet through the Hall effect device and back to the magnet.

Magnetic Field:

As the vane passes through this opening, the flux lines are shunted through the vane and back to the magnet.

During this time, a voltage is produced as the vane passes through the opening. When the vane clears the opening, the window edge causes the signal to drop to almost zero volts. The signal is then used by the PCM for crankshaft position sensing and the computation of the desired spark advance based on engine demand and calibration. The conditioned spark advance and voltage distribution is accomplished through the distributor rotor, distributor cap and distributor to spark plug wires.

The ICM, ignition coil, CMP sensor, stator, and radio interference capacitor are all integral parts of the distributor. If any of these components require service, the distributor must be replaced as a unit.