A power-train control module, abbreviated PCM, is an automotive component, a control unit, used on motor vehicle
A motor vehicle, also known as a motorized vehicle, automotive vehicle, automobile, or road vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on railway track, rails (such as trains or trams), does not fly (such ...
s. It is generally a combined controller consisting of the engine control unit
An engine control unit (ECU), also called an engine control module (ECM), is a device that controls various subsystems of an internal combustion engine. Systems commonly controlled by an ECU include the fuel injection and ignition systems.
The ...
(ECU) and the transmission control unit
A transmission control unit (TCU), also known as a transmission control module (TCM), or a gearbox control unit (GCU), is a type of automotive ECU that is used to control electronic automatic transmissions. Similar systems are used in conjunctio ...
(TCU). On some cars, such as many Chryslers, there are multiple computers: the PCM, the TCU, and the Body Control Module (BCM), for a total of three separate computers. These automotive computers are generally very reliable. The PCM commonly controls more than 100 factors in a car or truck. There are many hundreds of error codes that can occur, which indicates that some subsection of the car is experiencing a problem. When one of these errors occurs, usually it will turn on the "check engine" light on the dashboard. The PCM is one of potentially several on-board computers, or essentially the "brain" of the engine control system.
The primary inputs to the PCM come from many sensors, of different types, that are spread around the car. Most of them are oriented toward engine management and performance. These sensors fail at a much higher rate than any of the computers do.
Early use of the powertrain control module dates back to the late 1970s - official phasing in of the PCM occurred during the early 1980s when used in conjunction with electronic controlled carburetor
A carburetor (also spelled carburettor or carburetter)
is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...
s and lockup torque converters (at the time conventional 3-speed automatics received lockup converters at the same time overdrives were introduced).
Other names
Engine control unit is also called: * PCM: Power-train control module (Ford, GM, JLR) * ECM: Engine control module * Injection control unit (Peugeot
Peugeot (, , ) is a French automobile brand owned by Stellantis.
The family business that preceded the current Peugeot companies was established in 1810, making it the oldest car company in the world. On 20 November 1858, Émile Peugeot applie ...
, Citroën
Citroën ()The double-dot diacritic over the 'e' is a diaeresis () indicating the two vowels are sounded separately, and not as a diphthong. is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded on 4 June 19 ...
, Fiat
Fiat Automobiles S.p.A., commonly known as simply Fiat ( , ; ), is an Italian automobile manufacturer. It became a part of Fiat Chrysler Automobiles in 2014 and, in 2021, became a subsidiary of Stellantis through its Italian division, Stellant ...
, Alfa, Lancia
Lancia Automobiles S.p.A. () is an Italian car manufacturer and a subsidiary of Stellantis Europe, which is the European subsidiary of Stellantis. The present legal entity of Lancia was formed in January 2007 when its corporate parent reorganise ...
)
* DME/DDE: Digital Motor Electronics / Digital Diesel Electronics (BMW
Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...
, Mini
The Mini is a very small two-door, four-seat car, produced for four decades over a single generation, with many names and variants, by the British Motor Corporation (BMC) and its successors British Leyland and the Rover Group, and finally ...
)
* ECU: Electronic control unit / Engine control unit
Bibliography
* *References
{{Reflist Power control Engine technology Fuel injection systems Engine components Onboard computers Auto parts