Tahoe 2WD V8-4.8L VIN V (2004)
Crankshaft Position Sensor: Description and Operation
CRANKSHAFT POSITION (CKP) SENSOR
The crankshaft position (CKP) sensor is a three wire sensor based on the magneto resistive principle. A magneto resistive sensor uses two magnetic
pickups between a permanent magnet. As an element such as a reluctor wheel passes the magnets the resulting change in the magnetic field is used by
the sensor electronics to produce a digital output pulse. The PCM supplies a 12-volt, low reference, and signal circuit to the CKP sensor. The sensor
returns a digital ON/OFF pulse 24 times per crankshaft revolution.
CRANKSHAFT RELUCTOR WHEEL
The crankshaft reluctor wheel is mounted on the rear of the crankshaft. The wheel is comprised of four 90 degree segments. Each segment represents
a pair of cylinders at TDC , and is further divided into six 15 degree segments. Within each 15 degree segment is a notch of 1 of 2 different sizes.
Each 90 degree segment has a unique pattern of notches. This is known as pulse width encoding. This pulse width encoded pattern allows the PCM to
quickly recognize which pair of cylinders are at top dead center (TDC). The reluctor wheel is also a dual track-or mirror image-design. This means
there is an additional wheel pressed against the first, with a gap of equal size to each notch of the mating wheel. When one sensing element of the CKP
sensor is reading a notch, the other is reading a set of teeth. The resulting signals are then converted into a digital square wave output by the circuitry
within the CKP sensor.
