LeSabre V6-3.8L VIN K (1996)
Crankshaft Position Sensor: Description and Operation
The Crankshaft Position (CKP) Sensor provides a signal used by the ignition control module to calculate ignition sequence. The ignition control
module also uses the crankshaft position sensor signals to initiate 18X and 3X reference pulses which the PCM uses as reference to calculate RPM
and crankshaft position.
The dual crankshaft position sensor is secured in an aluminum mounting bracket and bolted to the front left side of the engine timing chain cover,
partially behind the crankshaft balancer. A 4-wire harness connector plugs into the sensor, connecting it to the ignition control module.
HALL-EFFECT SWITCHES
The dual crankshaft position sensor contains two Hall-effect switches with one shared magnet mounted between them. The magnet and each
Hall-effect switch are separated by an air gap. A Hall-effect switch reacts like a solid state switch, grounding a low current signal voltage when a
magnetic field is present. When the magnetic field is shielded from the switch by a piece of steel placed in the air gap between the magnet and the
switch, the signal voltage is not grounded. If the piece of steel (called an interrupter) is repeatedly moved in and out of the air gap, the signal
voltage will appear to go ON - OFF - ON OFF - ON - OFF.
Components
LEGEND
(1) Crankshaft Balancer
(2) Interrupter Rings
INTERRUPTER RINGS
Compared to a conventional mechanical distributor, this ON - OFF signal is similar to the signal that a set of breaker points in the distributor
would generate as the distributor shaft turned and the points opened and closed. In the case of the electronic ignition system, the piece of steel is
two concentric interrupter rings mounted to the rear of the crankshaft balancer.
Each interrupter ring has blades and windows that either block the magnetic field or allow it to close one of the Hall effect switches. The outer
Hall effect switch produces a signal called the CKP 18X because the outer interrupter ring has 18 evenly spaced blades and windows. The CKP
18X portion of the crankshaft position sensor produces 18 ON - OFF pulses per crankshaft revolution.
