Aspire L4-81 1.3L SOHC (1994)
Hall Effect Sensor: Description and Operation
Figure 7 - Magnetic Flux Field
PURPOSE
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 (ICM).
LOCATION
The Hall effect sensor is integral with the distributor. If the Hall effect sensor requires service, the distributor must be replaced.
Rotary Vane Cup
Magnetic Field
OPERATION
A rotary vane cup is used to trigger the signal off and on.
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.
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.
CONSTRUCTION
The rotary vane cup is made of ferrous metal.
The vane switch is an encapsulated package consisting of a Hall effect device on one side and a permanent magnet on the other side.
