The Powertrain Control Module (PCM) and Engine Control Module (ECM) are terms often used interchangeably, but they serve distinct purposes. The PCM oversees not only the engine but also the transmission system, integrating multiple control modules into a unified unit. On the other hand, the ECM focuses solely on engine-related functions, excluding transmission control. In conclusion, understanding the vital role of ECU, PCM, and ECM in your vehicle's performance is crucial for maintaining opt...