Crankshaft Position Sensor: Description and Operation

CRANKSHAFT POSITION (CKP) SENSOR




The crankshaft position (CKP) sensor (1) is located in the front cover of the cylinder block near the crankshaft pulley. The CKP sensor is actually two separate sensors, located 22.5 degrees apart, within the same housing. Both CKP sensor A and CKP sensor B function the same and provide 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 information from both CKP sensors in order to perform the following functions:
- Determine engine speed
- Determine accurate crankshaft position
- Calculate ignition system and fuel injection timing
- Provide continued engine operation even when one sensor fails
- Report engine misfire-when used with CMP sensor input

Operation




The CKP sensor signal rotor (1) is an integral part of the crankshaft pulley (3) and is located behind the timing belt cover. 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 tooth on the crankshaft signal rotor. The rotor has 24 evenly spaced teeth, with two teeth missing, indicating top dead center (TDC) and producing 22 electrical pulse per revolution. CKP sensor A and CKP sensor B each provide position signals to the PCM. The PCM relies on the signal from CKP sensor A first, and uses the signal from sensor B only when sensor A is missing or unintelligible.