What is an ECU, PCM, and ECM? Electronic Control Unit (ECU) is a generic term describing any embedded system that controls one or more of a vehicle's electronic systems. The Powertrain Control Module (PCM) is a type of ECU that manages the engine and transmission functions, while the Engine Control Module (ECM) specifically oversees the engine's operation. Reliable ECU, PCM, or ECM Solutions at Flagship One, Inc At Flagship One, Inc., we specialize in providing high-quality ECU, PCM, and ...