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

Shown on engine 120 

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 1: Locating Left And Right Crankshaft Position Sensor - Shown On Engine 120
G04736509
Fig 2: Identifying Left And Right Crankshaft Position Sensor Function
G04736510

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:

Engine Recognition of TDC position of cylinder
111 1 and 4
119, 104, 112, 113 1 and 6
120 Right hand cylinder bank: 1 and 6
Left cylinder bank: 7 and 12
137 1 and 7