Circuit Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

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 the engine is running and the CKP synchronizing pulses are being received. The Powertrain Control Module (PCM) uses the 3X reference signal to calculate the engine RPM and the CKP at engine speeds greater than 1600+/-150 RPM. The PCM also uses these pulses to initiate injector pulses. The PCM compares the 3X reference pulses to the 24X CKP pulses and the Camshaft Position (CMP) pulses. If the PCM receives an incorrect number of pulses on the 3X circuit a DTC P1374 will set and the 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 CMP sensor signals.