Distributor: Description and Operation

Typical Hall Effect Distributor Assembly:

Ignition Distributor (Engines W/Computer Controlled Ignition Timing):

The distributor, located on the rear of the cylinder head, is driven by the camshaft and rotates at the same rate (1/2 the rpm of the crankshaft). The distributor assembly consists of the distributor housing, cam driven shaft, hall sensor, hall trigger wheel, rotor, and cap. The distributor is installed in a position so that as it turns and a spark is generated by the ignition coil, the rotor is always pointing at the appropriate terminal of the cap to direct the spark energy to the correct cylinder.
Although the actual ignition timing is controlled by the ECU, it is important that the distributor installed position is correct, since the hall sensor in the distributor provides a reference signal from which the ECU calculates crankshaft position.