Control Modules

A control module or unit is a generic term that identifies an electronic unit that controls one or more electrical systems in the vehicle. Vehicles may have many control units installed, each with a specific purpose. For example, there are engine, transmission, body and suspension, entertainment, anti-theft, and many other control units. Control modules monitor a number of inputs from sensors and circuits, process those data according to the information programmed into their memory, and send output commands to actuators and electrical devices, which control the operation of various components and systems on the vehicle. On modern vehicles, the control units share information on a data bus, which is a common set of wires that connect the modules together so that information or data can be shared across the network. For example, the transmission control unit needs to know road speed, as does the control unit that operates the dash instruments and the anti-lock brake system control unit. The information from the one vehicle speed sensor is shared across the data bus to all three control units.