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Electronic Control Unit Explained

Electronic Control Unit Explained by type
Electronic Control Unit, or ECU, is a generic term for an embedded system within a vehicle that controls one or more of the electrical systems or subsystems.  There are many different types of systems, and below is a list a short explain for each of these systems. 



ECM - Engine Control Module - This unit controls a series of actuators on an internal combustion engine and ensures that optimum running conditions are present. It achieves this by monitoring values from a multitude of sensors within the engine compartment, interpreting the data using multidimensional performance maps, and adjusting the engine actuators accordingly.  Commonly named sensors are Oxygen Sensors, Camshaft Sensors, Crankshaft sensors, etc...  Commonly named actuators are Fuel Injectors and Ignition systems.

PCM - Powertrain Control Module - see ECM above.  This unit can also be a combination of the ECM and TCM. This is the main control module is all vehicles, responsible for over 100 different factors. 

TCM - Transmission Control Module - This unit controls the standard electronically shifted automatic transmission. A TCM will generally use sensor readingss from the vehicle in combination with data provided by the ECU to calculate how and when to upshift or downshift gears in the vehicle for optimum performance, fuel economy, and shift quality.

BCM/EBCM - Brake Control Module - This is associated with the Anti-Lock Brake system (ABS) within your vehicle.

BCM - Body Control Module - This unit is responsible for monitoring and controlling various electronic accessories in a vehicle's body such power windows, power seats, air conditioning systems, etc...

SCM - Suspenion Control Module - This unit controls and monitors any vehicle equipped with an electronic suspension system.  Various sensors on the different suspension components are monitored and allow adjustments as needed to improve handling characteristics and ride quality.
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