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 18X reference pulses from the ignition control module (ICM) to calculate engine RPM and crankshaft position at engine speeds below 1,200 RPM. The 18X signal is passed from the ICM to the PCM on the medium resolution engine speed signal circuit. The 3X signal is passed from the ICM 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 3X reference pulses. The PCM will use the low-resolution engine speed signal circuit for fuel injection and ignition control. If the PCM detects and incorrect number of 18X pulses during two crankshaft revolutions, DTC P0336 sets.