What is an ECU, PCM, and ECM? An Engine Control Unit (ECU), also known as a Powertrain Control Module (PCM) or Engine Control Module (ECM), serves as the brain of your car, regulating various systems to ensure efficient operation. These modules control critical functions like fuel injection, ignition timing, emissions, and more, optimizing performance and fuel efficiency. What is a PCM? The Powertrain Control Module (PCM) is a more encompassing term that includes the ECU along with transm...