C 3500 HD Truck 2WD V8-8.1L VIN G (2002)
Crankshaft Position Sensor: Description and Operation
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 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.
