Crankshaft Reluctor Wheel

WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.

The crankshaft reluctor wheel is mounted in the middle of the crankshaft. The wheel is comprised of three 120 degree segments. Each segment represents a pair of cylinders at top dead center (TDC) and is further divided into six 20-degree segments. Within each 20-degree segment is a notch of 2 different sizes. Each 120 degree segment has a unique pattern of notches. This is known as pulse width encoding. This pulse width encoding pattern allows the powertrain control module (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 wheel with a gap of equal size to each notch of the mating wheel. When one sensing element of the crankshaft position (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.