PCM

📖 YOUCANIC Automotive Glossary

The PCM (Powertrain Control Module) integrates both engine management and automatic transmission control into a single computer. Rather than separate ECU and TCM, vehicles with a PCM use one module for both systems, allowing tighter integration between engine torque and transmission shift strategy. The PCM controls fuel injection, ignition timing, emissions, and all engine functions while simultaneously managing shift points, line pressure, torque converter lockup, and shift quality. This allows the PCM to reduce torque during shifts and coordinate downshifts with throttle input.

PCM is most commonly used by Ford, GM, and Chrysler/Stellantis, while others may use separate ECU and TCM. When your scanner shows U0100 (Lost Communication with ECM/PCM), the module in question is whichever computer controls the engine in your vehicle. PCM replacement requires programming with VIN, calibration data, immobilizer keys, and possibly transmission-specific adaptation data. Always verify whether your vehicle uses a PCM or separate ECU/TCM before ordering replacement modules.