The electronic control unit (ECU) used in today’s cars and trucks is used to control the functions of the engine and other car components. An ECU is a computer with internal pre-programmed and programmable computer chips that is not much different from any other computer or a laptop.
The vehicle’s engine computer unit ECU is used to operate the engine by using input sensors and output components to control all engine functions.
The ECU needs inputs from vehicle sensors like the crankshaft sensor and camshaft sensors to compute the information using a program that has been stored in the ECU on a programmable memory chip. The ECU program will use the inputted sensor information to compute the needed output like the amount of fuel injected and when to spark the coil in order to start the engine.
There are different ECUs used for different systems on the vehicle. The different ECUs used can be for the transmission, traction control or ABS, AC, body functions and lighting control, engine, air bags, or any other system a vehicle may have. Some vehicles may incorporate more than one ECU into a single unit called a powertrain control module (PCM).