Circuit Description

The camshaft position (CMP) sensor works in conjunction with the 1X reluctor trigger wheel on the front of the camshaft gear. The engine control module (ECM) provides a 12-volt reference to the CMP sensor, as well as a low reference and a signal circuit. As the camshaft gear rotates, the reluctor trigger wheel interrupts a magnetic field produced by a magnet within the sensor. The CMP sensor internal circuitry detects this interruption of the magnetic field and produces a signal, which the ECM reads. The 1X signal produced by the CMP sensor is used by the ECM to determine if the cylinder at the top dead center (TDC) is on the firing stroke or the exhaust stroke. The ECM can determine TDC for all cylinders by using the crankshaft position (CKP) sensor 24X signal. If the 1X signal is not received by the ECM, a slightly longer cranking time may be experienced. The ECM will attempt synchronization and looks for an increase in engine speed, indicating that the engine is running. If the ECM does not detect an increase in engine speed, the ECM assumes that it incorrectly synchronized to the exhaust stroke, and then will synchronize to the opposite cam position. If the ECM detects that there is no output signal from the CMP sensor, DTC P0340 will set.