Electronic control unit

In automotive electronics, 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 motor vehicle. Some modern cars have up to 80 ECUs, including:
 * Engine Control Unit - also known as an ECU
 * Transmission Control Unit - TCU
 * the above two may be combined, and referred to as a Powertrain Control Module (PCM)
 * Airbag control unit - ACU
 * Telephone Control Unit - TCU dials telephones for you and talk to your friends
 * Man Machine Interface - MMI
 * Body Control Module - controls door locks, electric windows, courtesy lights etc.
 * 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 original equipment manufacturers (OEMs).

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