Crankshaft Position Sensor (7/25) [2019-2022]: Description
The crankshaft position sensor consists of four hall sensors, permanent magnets and internal electronics. The sensor detects the stamped holes on the flywheel rim. The holes are positioned with a 6 degrees distance between each hole.
The flywheel rim has a "gap" and gives the crankshaft position sensor 60-4=56 pulses per crankshaft revolution. When the Engine Control Module (ECM) has identified the reference gap, the control module can determine the exact position of the crankshaft by counting pulses. When the reference gap on the flywheel passes below the sensor, the voltage and the frequency instantly drop to zero. The first hole after the reference gap is located 84° before the top dead center on cylinder 1.
The crankshaft position sensor has different signal characteristics depending on the direction of the crankshaft rotation. The Engine Control Module (ECM) stores the crankshafts position during the driving cycle. This means that the ECM knows which cylinder is nearest in turn for injection and ignition at the next start after the engine was switched off during Start/Stop. The engine can therefore be started without having to "search" for a synchronizing position between the crankshaft and the camshafts. This reduces the time needed for cranking, which in turn leads to a reduced load on the batteries and the starter motor. This is especially important when starting during a Start/Stop sequence. If the driving cycle is interrupted the stored crankshaft position is removed from the ECM's memory.