The role of the ECU control system

ECU – also known as the black box, is the control brain, and is the most important part of a car. Do you clearly understand the role of this system? Join CarOn to learn more through the article below!

What is ECU?

ECU is an abbreviation for the phrase Electronic Control Unit, meaning electronic controller, or in the worker’s own language, it is also called “Black Box”, ECU is like a computer or “Brain” for control. the operation of almost all systems on the car.

The ECU is a combination of electronic circuits and sub-components used to recognize signals, as well as store information, calculate, and send appropriate signals, and finally determine the working function. of the vehicle so that it is most reasonable and effective in different situations.

Structure of the ECU control system

The ECU is made up of 3 main parts: memory in the ECU, microprocessor (brain of the ECU) and transmission line – BUS.

Memory in ECU

This part will include four small components with different roles

  • ROM element (Read Only Memory): Has the role of reading pre-programmed information independently, not writing, used to store permanent information. And ROM is the place to provide information to the processor, also known as temporary memory.
  • RAM element (Random Access Memory): Considered a memory used for random access, storing information recorded in memory and determined by the microprocessor. It can read and write any data to any address.
  • PROM element (Programmable Read Only Memory): Here, it allows modifying the control program at different times. Has the same basic structure as ROM, but allows programming.
  • KAM element (Keep Alive Memory): Any information provided to the processor in temporary form will be stored in KAM. When the car engine stops working or is turned off, this memory still maintains its memory. But if you remove the power supply from the battery to the computer, the memory will be lost.


This is considered the brain of the ECU, because it has the function of information from sensors, analysis and making decisions.

From receiving signal information from the sensors on the engine through the memories in the ECU, the signal is immediately sent to the microprocessor. At that time, this part has the function of calculating and giving orders to the appropriate execution part. This is considered the most important part of the ECU


The BUS transmission line is used to transfer commands and data in the ECU.

It can be understood that in order for information to be transmitted from the microprocessor to the actuators as quickly as possible, the transmission line plays a significant role. Previously, computer control engines used 4, 8, or 16 bit types, the most common being 4 and 8 bit types. A 4-bit computer holds a lot of instructions because it executes logical instructions better. 8-bit computers work better with algebra and are 16 times more accurate than 4-bit computers.

Therefore, today to control various systems in cars with fast execution speed and high accuracy, people often use 8-bit, 16-bit or 32-bit computers.

Operating principle of the ECU control system

The interdependence between the ECU and the engine speed sensor system and pistons determines the operating principle of this part.

Input: Information from sensor devices such as speed sensor, temperature, intake air flow, etc. And on and off signals, data from the modules will be collected by the car ECU.

Handle: The microprocessor element in the ECU will begin to determine the output specifications as directed by the software stored in the device. From there, the ECU makes decisions for the appropriate parts using commands.

Output: Through receiving data from sensors, the car ECU conducts control work and manages all engine activities.

  • To ensure the engine operates efficiently, the ECU helps provide very accurate output.
  • Adjust the fuel injector open time by controlling the injector pulse width.
  • Receive signals from the sensor to decide on the correct operating time of the ignition system.
  • The throttle part is controlled by the ECU through the motor. Helps throttle opening angles reach their maximum value.

What effect does ECU have on cars?

ECU has the ability to help control all engine activities to provide the vehicle with stability, accuracy, optimality and extreme safety. Parts such as ignition, fuel pump, engine throttle, cam timing, or braking force, etc. all comply and always follow the decisions made from the electronic control unit ECU.

The ECU is the “brain” that controls and governs all engine activities through receiving sensor data. The ECU processes the signal, then issues “commands” forcing the actuators to perform such as fuel control, ignition angle, cam timing angle, automatic throttle, six brakes at each wheel,…

Besides, the actuator must always ensure to follow ECU commands and respond to feedback signals from sensors to provide the necessary accuracy and adaptation. At the same time, minimize harmful substances in exhaust gases and improve fuel consumption, ensuring optimal power in engine operating modes. Furthermore, the ECU intervenes and quickly handles situations where the driver loses control and when in danger, especially helping to diagnose engine “diseases” quickly.

On today’s modern car models, the ECU may be a microchip combination used to recognize signals, store information, calculate, send appropriate signals and decide how the vehicle functions. for the most effectiveness in different situations.

Some signs of damage to the ECU system

Automotive ECU plays a very important role in the operation of today’s modern cars. Therefore, any problem that occurs with this part will seriously affect the entire engine system, even causing the vehicle to stop operating. Below are some common signs of ECU problems:

The Check Engine light (engine error light) lights up

The reason is because the car’s ECU detects that the circuit components, sensors, etc. are having problems. However, this situation sometimes occurs due to confusion with the electronic controller. Therefore, to determine the exact cause, car owners just need to scan the trouble codes according to the manufacturer’s instructions.

Learn more about the engine error light status through the article above

Engine malfunction

If the ECU has a problem, the engine will experience some problems such as stalling or difficulty accelerating. Because the electronic control unit performs the function of controlling fuel supply through the process of evaluating air intake volume, throttle position, camshaft and crankshaft, when this part fails, the connections will occur. occurs intermittently with one or more different sensors, causing the engine to operate abnormally.

Poor engine performance

This is a sign that the ECU is failing. This causes the process of adjusting the fuel supply to be incorrect, causing the ignition timing to be inaccurate. As a result, the engine’s performance is reduced, the vehicle feels sluggish and has difficulty accelerating.

Car is difficult to start

This is the case when the ECU is completely damaged, causing the engine management process to be interrupted, making it difficult for the vehicle to start or even unable to operate.

Fuel consumption is high

car is hard to start caron

The ECU provides the correct fuel level for the combustion process by monitoring moving conditions such as throttle position, current engine load, etc. One of these values ​​is incorrect, leading to the engine running. less efficient engine and higher than normal fuel consumption.

Reputable address for ECU maintenance and repair

ECU is an important part, considered the “brain” of the vehicle, directly affecting the engine’s performance. During use, damage or reduced performance cannot be avoided. Therefore, users should regularly take their vehicles to maintenance centers to support periodic inspection, early detection and treatment of damage to ensure safety when driving the vehicle.

So where is the reputable address to “choose where to send gold”? Come immediately to CarOn – a popular brand today.


Outstanding product quality, superior warranty service, CarOn is confident that it is a worthy place for you to entrust your beloved car.

Contact us immediately via hotline: 0961.247.360 or website for the fastest advice and support!

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