GMC 12597254 Sensor Assembly, Crankshaft Position

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The Crankshaft Position (CKP) sensor provides the PCM with a crankshaft position signal, which the PCM uses to determine the spark sequence for each cylinder, control ignition timing, and calculate engine speed. The signal is also used by the Onboard Diagnostic system for misfire detection. The sensor is triggered by slots cut into a reluctor ring on the crankshaft and is positioned approximately 0.050 inch from the reluctor ring. As the notches pass the sensor, the magnetic field is altered, producing a pulsating voltage. The ignition system will not operate if the PCM does not receive a crankshaft position sensor input. When replacing the sensor, the PCM must be reprogrammed using special equipment and a crankshaft sensor variation relearn procedure must be performed using a special TECH 2 scan tool. This should be done by a dealer service department or other qualified automotive repair facility. To replace the sensor, disconnect the cable from the negative battery terminal, raise the vehicle and support it securely on jackstands, disconnect the electrical connector from the sensor, remove the sensor mounting bolt and the sensor itself. Installation is the reverse of removal.