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AutoPi > Blog > What is an Electronic Control Unit (ECU)?

What is an Electronic Control Unit (ECU)?

Updated at 25 Mar, 2021

— Electronic Control Unit (ECU) is a small device in vehicles that controls a specific function, such as engine, power steering control, windows and many more.

What is an Electronic Control Unit (ECU)?
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Electronic Control Unit (ECU) is commonly used in today’s vehicles. Its purpose is to control the engine or other components’ functions.

An ECU is a very small car computer (carputer) with internal chips that are very similar to the ones we have at home, such as a laptop.

Each of a vehicle’s electronic features are typically controlled by an ECU. The term ECU is also commonly referred to Engine Management Systems - Engine Control Units.

Read: ISOBus

What is ECU?

ECU stands for Electronic Control Unit and it is a small device within each vehicle that is responsible for controlling a specific function.

Modern vehicles can consist of more than 80 ECUs nowadays. They control essential functions, such as engine or power steering control to comfort functions, such as windows or seats.

In addition, ECUs can control security and access of a vehicle, such as keyless entry, airbags or emergency braking. In order to make it easier to understand, we will give you an example below.

Let’s say an airbag ECU would receive inputs when the vehicle crashes, as well as detect if somebody is sitting in the particular seat.

Then, the ECU would communicate with actuators to perform an action based on the specific situation, such as the airbag function. Meaning that the airbag ECU would choose which airbag to deploy.

ECU Manufacturers

There are many types and manufacturers that make ECUs, therefore, we will give you the most common types. Find them below:

  • Bosch.

  • Ford.

  • Siemens.

  • Delco.

  • Delphi.

  • Sagem.

  • Melco.

An easy illustration of Electric Control Unit

Electronic control unit (ECU) is also known as electronic control module (ECM).

Types of ECU include Powertrain Control Module (PCM), Transmission Control Module (TCM) Brake Control Module (BCM or EBCM), Central Control Module (CCM), Central Timing Module (CTM), General Electronic Module (GEM), Body Control Module (BCM) and Suspension Control Module (SCM).

Electronic Control Unit banner

However, the more functions the vehicle has, the more ECUs. Therefore, has become the major challenge for manufacturers, as the space in each vehicle is limited.

ECU consists of both software and the hardware. Automotive ECUs are developed by following the V-model. ISO 26262 standard is being used to develop safe modules.

People generally try to modify their ECU, in order to be able to change its functionality. Unfortunately, modern ECUs are equipped with protection locks to prevent its users from doing that.

ECUs are closely connected to the protocols, such as CAN Bus, CAN FD, CANopen,LIN Bus, J1939 and more. Check them out to find out more about Electronic Control Units and how they are applied in each protocol.

History of the ECU

1970s - Electronic Control Units started controlling a couple of functions, such as solenoids on carburetors. Later, some of them even started controlling the mixture at idle speed.

1980s - ECUs slowly became completely responsible for the fuel and ignition management of petrol engines, with the help fuel injection being introduced.

1990s - The vehicle security also became a part of ECUs and started slowly appear on diesel engines.

2000s - ECU started having a tight control over drive-by-wire throttle control, turbocharger control, and numerous emission systems.

2010s and beyond - ECU having a full control over previously mentioned systems. It can have more than a hundred inputs and outputs.

What Happens If An ECU Is Dead?

If an ECU is dead, the car will not start as the ECU controls the engine ignition. It might also affect different parts of the vehicle too, but that might not be relevant anymore as you car cannot be simply started.

What happens If An ECU Is Faulty?

A faulty ECU can be very problematic for you and your vehicle. I will most likely work, but will be affected by its performance negatively. Some of the signs can be: the check engine light is on, the car will not start, weird gear shifts, higher fuel consumption, and more.

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