Malibu V6-191 3.1L VIN M SFI (1997)
Crankshaft Position Sensor: Description and Operation
Crankshaft Position (CKP) Sensor 24X
24X Crankshaft Position (CKP) Sensor
DESCRIPTION
The 24X crankshaft position sensor (1), secured in, an aluminum mounting bracket and bolted to the front left side of the engine timing chain cover, is
partially behind the crankshaft. A 3-wire harness connector plugs into the sensor, connecting it to the Powertrain Control Module (PCM). The 24X
Crankshaft Position (CKP) Sensor is used to improve idle spark control at engine speeds up to approximately 1250 RPM.
OPERATION
The 24X crankshaft position sensor contains one Hall-effect switch and magnet. The magnet and 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. 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 the concentric interrupter ring
mounted to the rear of the crankshaft balancer. The interrupter ring has blades and windows that, with crankshaft rotation, either block the magnetic field
or allow it to close the Hall-effect switch. The Hall-effect switch produces a signal called the CKP 24X because the interrupter ring has 24 evenly spaced
blades and windows. When a CKP 24X interrupter ring window is between the magnet and Hall-effect switch, the magnetic field will cause the CKP
24X Hall-effect switch to ground the CKP 24X signal voltage supplied from the PCM. The CKP 24X portion of the crankshaft position sensor produces
24 ON-OFF pulses per crankshaft revolution. The 24X signal allows the PCM to determine a more precise crankshaft position at lower RPM.
