Ignition Hall Effect Sensor: Description and Operation

PURPOSE

The engine speed input is supplied to the engine controller by the distributor pick-up. The distributor pick-up is a Hall Effect device.

OPERATION

A shutter (sometimes referred to as an interrupter) is attached to the distributor shaft. The shutter contains one blade per engine cylinder (8 blades).

A switch plate is mounted to the distributor housing above the shutter. The switch plate contains the distributor pick-up (a Hall Effect device and magnet) through which the shutter blades rotate. As the shutter blades pass through the pick-up, they interrupt the magnetic field.

The Hall effect device in the pick-up senses the change in the magnetic field. It then switches on and off (creating pulses), generating the input signal to the engine controller. The engine controller calculates engine speed through the number of pulses generated. The engine speed input is also used to control coil dwell.