Theory Of Operation

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The Camshaft Position (CMP) sensor circuits consist of a Powertrain Control Module (PCM) supplied 5-volt circuit, low reference (ground) circuit, and an output signal circuit. The CMP sensor is an internally magnetic integrated circuit sensing device. The sensor detects magnetic flux changes between the peaks and valleys of a reluctor wheel attached to the camshaft. As each reluctor tooth rotates past the CMP sensor, the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The sensor returns a digital ON/OFF (HIGH/LOW) DC voltage pulse of varying frequency. The output pulses per camshaft revolution represent an image of the camshaft reluctor wheel. The frequency of the CMP sensor output depends on the velocity of the camshaft. The PCM decodes the tooth pattern to identify camshaft position. This information is then used to sequence the ignition timing and fuel injection events for the engine. The PCM also uses CMP sensor output information to determine the camshaft relative position to the crankshaft, to control the CMP actuator operation if equipped.