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Crankshaft position sensor function - GF07.04-P-4116-01M

Fig 1: Identifying Crankshaft Position Sensor With Missing And Incremental Gear Teeth Of Driven Plate
G07618520Courtesy of MERCEDES-BENZ USA

Crankshaft position and engine speed are detected contactlessly. The clearance between crankshaft position sensor (L5) and the teeth (d) of the drive plate (incremental gear) is fixed by the installation position (approx. 0.8 mm).

When the crankshaft is rotating, an alternating voltage is generated (induced) in the crankshaft position sensor by the teeth of the driven plate.

Fig 2: Signal Of Crankshaft Position Sensor
G07618521Courtesy of MERCEDES-BENZ USA

The leading edge of a tooth (a) generates a positive voltage pulse and the trailing edge (b) a negative voltage pulse. The distance from the positive to the negative voltage peak corresponds to the length of a tooth.

The gap produced by 2 missing teeth (c) results in no voltage being generated in the crankshaft position sensor (L5). This point serves for detecting the TDC position of cylinder 1 and 7.