Distributor: Description and Operation

NOTE: This vehicle is equipped with a camshaft driven mechanical distributor containing a shaft driven distributor rotor and equipped with an internal camshaft position (fuel sync) sensor. This sensor provides fuel injection synchronization and cylinder identification.
The distributor distributes high voltage secondary output through the rotor and distributor cap and spark plug wires to the spark plugs.

Typical Distributor:

PURPOSE
The camshaft position (CMP) sensor signal is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.The CMP sensor is located in the distributor.

OPERATION
The CMP sensor contains a hall effect device called a sync signal generator to generate a field sync signal.
The CMP sensor detects a rotating pulse ring (shutter) on the distributor shaft. The pulse ring rotates 180 degrees through the sync signal generator.
When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approximately 5 volts.
When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync signal voltage to switch low to 0 volts.

NOTE: If the Powertrain Control Module (PCM) does not sense input from the CMP sensor, the PCM will deactivate automatic shut down and fuel pump relays, interrupting voltage to fuel pump, fuel injectors, and ignition coil, causing a no start condition.