Crankshaft Position Sensor: Description and Operation

Fig. 33 Crankshaft Position Sensor:

The crankshaft position sensor registers the crankshaft position and engine speed. The position sensor is mounted to the crankcase above the starter flange.

Fig. 32 Crankshaft Position Sensor Location:

The sensor body projects through the crankcase very near to the segments on the flywheel/drive plate. There is no contact between the segments or the position sensor.

Fig. 31 Ring Gear Position Segments:

With the engine running, the three segments which are positioned 120° apart pass by the position sensor. Due to induction, an alternating voltage is generated in the position sensor. The peak voltage is approx. 1.5 volts at starting speed. The voltage rises with increasing speed to approx. 3 volts at 1200 rpm.

Fig. 30 Crankshaft Position Sensor Signal:

t1 = First Segment
t2 = Second Segment
t3 = Third Segment
d = Period for one crankshaft rotation

The crankshaft position is recognized from the voltage signals which are produced. The segment front edge generates a negative voltage signal. The segment rear edge generates a positive voltage signal. Engine speed is determined by measuring the period (d) which is equal to one crankshaft revolution.