Cobalt L4-2.0L SC VIN P (2005)
Crankshaft Position Sensor: Description and Operation
CRANKSHAFT POSITION (CKP) SENSOR
The crankshaft position (CKP) sensor is a permanent magnet generator known as a variable reluctance sensor. The CKP sensor produces an AC voltage
of varying amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC output depends on the crankshaft position and the
battery voltage. The CKP sensor works in conjunction with a 58-tooth reluctor wheel attached to the crankshaft. As each reluctor wheel tooth rotates past
the CKP sensor, the resulting change in the magnetic field creates an ON/OFF pulse 58 times per crankshaft revolution. The PCM processes the pulses to
create a pattern that enables the PCM to determine the crankshaft position. The PCM can synchronize the ignition timing, the fuel injector timing, and
the spark knock control based on the CKP sensor and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and for
tachometer display. The PCM learns the variations between all 58 teeth under different speed and load conditions to correctly detect misfires. The CKP
sensor circuits consist of a signal circuit and a low reference circuit. The two wires are twisted together to prevent electromagnetic interference on the
CKP sensor circuits.
