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

Shown on engine 120 

Fig 1: Identifying Left And Right CKP Sensor - Shown On Engine 120

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function 

Crankshaft position and engine speed are detected contactlessly. The distance between crankshaft position sensor and the teeth of the driven plate is fixed by the installation position.

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

Fig 2: Identifying Left And Right CKP Sensor With Position Sensor Wiring Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The leading edge of a tooth generates a positive voltage pulse and the trailing edge 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 results in no voltage being generated in the crankshaft position sensor. This is analyzed for detecting the TDC position: