Crankshaft Hall Sensor, Basic Function - GF07.04-P-2004A

Engine All (4xWD) 

Engine All (CAR) 

Overview 

This document contains information on

• General 
• Function 

General 

The crankshaft Hall sensor contactlessly detects the increment structure (perforated plate) on the starter ring gear and forms an electrical signal (impulse pattern) based on this. The combustion engine control unit uses this signal as a basis on which to calculate the rotational speed and current angular position of the crankshaft.

Example illustration on engine M272 

Fig 1: Crankshaft Hall Sensor Components Location - Engine All (Car)

Courtesy of MERCEDES-BENZ USA

Function 

The crankshaft Hall sensor and its electronics are cast into a plastic housing with a 3-pin plug connection. The distance to the sensor rotor is determined by the installation position and is approx. 0.3 to 1.3 mm. The crankshaft Hall sensor scans the perforated plate with the 58 teeth and a gap of 2 teeth (60-2). Each of the 4 mm wide teeth generates a signal change at the crankshaft Hall sensor. The signal changes from each time from approx. 5 V (high) up to approx. 0 V (low). The rotational speed of the control unit and position of the crankshaft are calculated from the signals.

The top dead center of cylinder 1 is recognized by passing the gap with 2 missing teeth.