Circuit Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The powertrain control module (PCM) uses the 3X reference pulses from the ignition control module (ICM) to calculate engine RPM, and crankshaft position at engine speeds above 1,200 RPM. The 3X reference signal is produced by the ICM and passed to the PCM on the low-resolution engine speed signal circuit. The PCM constantly compares the number of 18X reference pulses to the number of 3X reference pulses and camshaft position signals being received. If this DTC sets, the engine will continue to start and run using the cam signal and 18X reference pulses. The PCM will use the medium-resolution engine speed signal circuit for fuel injection and ignition control. If the PCM detects an incorrect number of 3X pulses during two crankshaft revolutions, DTC P1374 sets.