Crankshaft Position Sensor: Description and Operation

The crankshaft position (CKP) sensor is located in the front cover of the cylinder block near the crankshaft pulley. The CKP sensor produces an AC signal that increases in both frequency and amplitude as the engine speed increases. The CKP sensor signal is sent to the PCM in order to indicate the RPM and the crankshaft position. The PCM uses the CKP sensor signal along with the camshaft position (CMP) sensor signal for the following purposes:
- To calculate the fuel injector pulse
- To establish the piston position top dead center (TDC) for the ignition timing
- To start the ignition coil and fuel injection sequencing

Operation




The CKP sensor reluctor (3) has 34 teeth and is mounted on the crankshaft behind the timing chain cover and the crankshaft pulley. When the crankshaft rotates, the CKP sensor signal rotor teeth pass by the CKP sensor (2) causing a fluctuation in the sensors magnetic field. The fluctuation in the magnetic field induces a voltage in the CKP sensor circuitry that corresponds to every 10 degrees of crankshaft rotation. The reluctor has one wide tooth (1) that indicates top dead center (TDC) of the number 1 cylinder. With the information that the PCM receives from the CKP sensor, the PCM determines engine speed and crankshaft position.