DTC P1374: 3X Reference Circuit: Description

The 3X reference signal is produced by the Ignition Control Module (ICM). The ICM calculates the 3X reference signal by dividing the Crankshaft Position (CKP) sensor 18X pulses by 3 when the engine is running and CKP sync pulses are also being received. The Powertrain Control Module (PCM) uses the 3X reference signal to calculate engine RPM and crankshaft position at engine speeds above 1200 RPM. The PCM also uses the pulses on this circuit to initiate injector pulses. The PCM constantly monitors the number of pulses on the 3X reference circuit and compares the number of 3X reference pulses to the number of 18X reference pulses and CAM signal pulses being received. If the PCM receives an incorrect number of pulses on the 3X reference circuit, DTC P1374 will set and the PCM will use the 18X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 18X reference and camshaft position PCM input signals only.