Section 03-07A: Ignition, Distributor | 1996 F-Series and Bronco with Gasoline Engines Workshop Manual |
The universal distributor (12127) has a Hall effect vane switch assembly to allow the ignition coil (12029) to be switched on and off by the powertrain control module (PCM) (12A650) and ignition control module (ICM) (12A297). The vane switch is an encapsulated package consisting of a Hall effect device on one side and a permanent magnet on the other side.
The distributor armature (12A099) is made of ferrous metal and is used to trigger the signal off and on.
When the window of the distributor armature 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 go to zero volts. This signal is used by the powertrain control module 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 done with a conventional distributor rotor (12200), distributor cap (12106) and spark plug wire set (12259).
