What are the functions of the crankshaft position sensor?

The function of the crankshaft position sensor is to control the ignition timing of the engine and confirm the signal source of the crankshaft position. In order to do so, the crankshaft position sensor detects the TDC signal of the piston and the crankshaft angle signal, and these signals could also be used to measure engine speed. 

So the crankshaft position sensor determines the position of the crankshaft through detecting the engine's crankshaft speed and angle. Then it transmits the results to the engine computer or other computers. Also camshaft position sensor is used to determine basic ignition time. The computer controls the ignition time, fuel injection time, and fuel injection amount of the engine based on the signal from the camshaft sensor. 

The crankshaft position sensor is usually installed at the front end of the crankshaft, camshaft, distributor, or flywheel. There are three structural forms of crankshaft position sensors: inductive, photoelectric, and Hall type. 

The crankshaft position sensor is installed on the transmission clutch housing, located behind the left side of the engine block. The crankshaft position sensor is fixed with two bolts. The bottom of the crankshaft position sensor is filled with adhesive paper or cardboard pads to adjust the depth of the sensor. Once the engine is started (after installing the crankshaft position sensor), the excess part of the paper pad should be removed. The new factory backup sensor should include this pad. If the original crankshaft position sensor is reinstalled or the transmission and clutch housing are replaced, a new gasket must be installed.