DTC P1374: Crankshaft Position High-To-Low Resolution Frequency Correlation: Description

The 3X reference signal is produced by the Ignition Control (IC) module. The IC module calculates the 3X reference signal by dividing the Crankshaft Position (CKP) sensor 7X pulses by 2 when engine is running and when CKP synchronizing pulses are being received. The PCM uses the 3X reference signal to calculate engine RPM and crankshaft position at engine speeds greater than 1600+/-150 RPM. The PCM also uses these pulses to initiate injector pulses. PCM compares the 3X reference pulses to the 24X CKP pulses and the Camshaft Position (CMP) sensor pulses.

If PCM receives an incorrect number of pulses on the 3X circuit, this DTC will set and PCM will use the 24X CKP reference circuit for fuel and ignition control. The engine will continue to start and run using only the 24X CKP and the camshaft position sensor signals.