What Is PCM (Powertrain Control Module)?
The Powertrain Control Module (PCM) is the computer that controls both engine and transmission functions as one unit. Manufacturers differ in whether they integrate these into a single module (PCM) or separate engine (ECM/ECU) and transmission (TCM) modules.
In plain English
PCM and ECU/ECM describe the same family of engine computers; the difference is scope. When a manufacturer combines engine and transmission control in one module, it's usually called a PCM.
For diagnostics, the distinction matters mostly for locating data and testing shared functions — for example, torque management, where the engine and transmission computers interact. Terminology varies by brand, so service data for the specific vehicle is the guide.
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