The ECM, also known as the engine control module, is a type of control module that manages various functions within the engine, such as fuel delivery, ignition timing, and emissions control. On the other hand, the PCM, or powertrain control module, is a more comprehensive control module that oversees not only the engine but also other key components within the powertrain, including the transmission. Check Engine Light: A persistent check engine light could indicate a malfunction within the EC...