Sensor, Crankshaft Position: Operation

The crankshaft position and engine speed are detected through a (hall effect) signal. The distance between the crankshaft position sensor and the gaps of the tone wheel is fixed by the installation position.
When the crankshaft rotates, an alternating voltage is generated in the crankshaft position sensor by the gaps of the tone wheel located behind the flexplate.
In this case, the metal portion of the tone wheel generates a positive voltage pulse and the gap in the tone wheel a negative voltage pulse. The distance from the positive to the negative voltage peak equals the length of the gap.