Specification :

an electronic control unit (ECU), also called a control unit, or control module, is an embedded system that controls one, or more, of the electrical systems or subsystems in a vehicle. Some modern cars have up to 80 ECUs, including:

* Engine Control Unit - also known as an ECU
* Transmission Control Unit - TCU
o the above two may be combined, and referred to as a Powertrain Control Module (PCM)
* Airbag control unit - ACU
* Telephone Control Unit - TCU
* Man Machine Interface - MMI
* Door Control unit
* Seat Control Unit
* Climate Control Unit
* speed control unit
* Convenience control unit - CCU

Managing the increasing complexity of ECUs and number of ECUs in a vehicle has become a key challenge for OEMs.

ECU -often called the brain of a car

In some older vehicles, the ECU is referred to as an ECM (electronic control module).