ECU: what is it and where is it located?

In this article, you will learn about a device like the ECU. What is it and for what purpose does it need a car? Now we will try to understand this. In recent years, cars have come out of production, in which fuel injection was carried out with a carburetor. Today, all machines are equipped with systems with forced injection. The principle of their work is much simpler, but the probability of breakage is greater. In particular, if one sensor comes out, the engine starts to work incorrectly.

How does the control unit work?

This device is also called the "brain". And in fact and the truth, this black box "thinks", how the engine should work in various modes. He controls the tens of parameters of the engine every second, chooses the most optimal percentage of air in a mixture with gasoline. Opens and closes in a timely manner the injectors, which supply fuel to the combustion chambers. Hardly anyone can think as quickly as the control unit. Not only sensors, but also actuators are connected to it . For example, the same injectors, as well as the idle speed regulator and others. To learn more about the principle of functioning, you need to consider the scheme of this device. But the schematic diagram of the computer is given in the article.

Internal computer control unit

At the heart of it lies the microcontroller. It has input and output ports to which all mechanisms and sensors are connected. Among the latter is worth highlighting the one that measures airflow. On his example will be considered how the signals are fed to the electronic control unit. All sensors are connected to the input ports either by special voltage dividers or amplifiers at the op amp. These are amplifying cascades on chips or FETs. They help to increase the level of the signal coming from the sensors. But the output ports are necessary for management. It is worth noting that the pinout of the computer in different cars is different. Therefore, the use of brains from Chevrolet on the Lada is unlikely to happen without significant alterations. For example, the injectors are connected to them. But not everything is so simple, the microcontroller's output port can only manage a weak load. In other words, the coil of the injector can not be directly connected to it. Therefore, special assemblies on field-effect transistors are installed between them. They allow you to amplify many times the signal from the controller. They are called Darlington assemblies.

Work algorithm

But without one component the microcontroller can not work - without the algorithm. Visually, it can be represented as a tree with many parameters. It contains all the "questions" that need to be answered by the electronic brain. For example, if the crankshaft rotational speed is 2000 rpm and the oxygen concentration is too low, the air flow rate is increased. What should the engine do in this case? The microcontroller immediately answers all these questions, leading the algorithm to solve the problem. And there and then produces a pulse feed to the output ports, causing the engine to work in a normal state. This is not otherwise than the firmware of the computer.

Where is the computer mounted?

It is installed on all injection cars. With its help, analysis and collection of all information that comes from sensors located on the internal combustion engine is performed . Unfortunately, the electronic unit sometimes fails. Therefore, it must be replaced with a new one. Before starting the repair, connected with the removal of the electronic unit, you need to de-energize the entire vehicle. To do this, disconnect the negative terminal from the battery. This will avoid accidental short circuits in the electrical circuit. Note that even a short-term short-circuit will easily trigger the output of certain elements, in particular semiconductors in the control unit, as well as fuses. Pay attention to the location of the computer. On the first cars "Lada Kalina", for example, it is located directly under the radiator of the stove. And if leakage occurs, the control unit immediately burns.

Removing the electronic control unit

If you take the example of the car VAZ 2107, then in it the computer (what is it, you already know) is under the dashboard, in the passenger's legs area. To make it more convenient to dismantle the device, you need to remove the shelf, which is directly under the glove compartment. To do this, you need to unscrew the screws, which it is attached to the parry. To provide access to the electronic control unit, it is also necessary to dismantle the bracket on which the fuses are located and the relays operating from this device. Now you can disconnect all the wires from the electronic unit. The body is fixed by means of two nuts to the body of the car. With the key on "10" it is necessary to unscrew these nuts and completely remove the control unit. That's all, the engine ECU is completely dismantled, it is ready for repair work or replacement. The installation of the new device is done in the reverse order.

Sensor diagnostics

Consider the example of a domestic car VAZ, where the DMRV is the most important element of accounting for all the characteristics that must be taken into account for the correct injection of fuel. As you already know, all the data that comes from this device, affect the operation of the entire engine. The firmware of the ECU is extremely important, and more precisely, it is a fuel card, which contains several important parameters. In particular, the amount of air and gasoline supplied to the ramp for the mixture formation, crankshaft speed and load on the motor. Before carrying out the replacement of this device, it is necessary to make a small diagnosis. Initial verification can be done with a conventional multimeter. With its help, it is necessary to check the voltage value, which is present at the sensor on the terminals.

To do this, disconnect the plug from it. Install the multimeter in the position where the voltage is measured. The negative wire is connected to the mass of the internal combustion engine. When the ignition is switched on, the voltage is measured at the fifth terminal in the plug coming to the sensor. The reference point should be kept at a value of about 12 volts. If there is a strong deviation, there is a fault in the engine ECU or the wiring to the sensor is faulty. The fourth pin should be about 5 volts. If there is a significant deviation from this value, then the cause of this is also a wiring fault, or it lies in the control unit itself.

Replacing the air flow sensor - stable operation of the engine and computer

Now you know about the ECU. What it is, for what purpose it is necessary, you know. It's time to talk a little about the measuring devices that affect its correct operation. It's quite easy to replace the sensor. To do this, use a Phillips screwdriver to loosen the clamp that secures the spigot. Next, remove the sleeve, which carries out air removal. After that, the key for "10" is to unscrew the two screws that secure the mass flow sensor directly to the air filter. After that, the sensor can be completely removed. Install the device in the reverse order. If you remove the sensor for cleaning, do not try to clean the spiral during work, touch it with your hands or other objects. Only spraying a spray onto the surface of a platinum wire is allowed.

Conclusion

You learned a bit about the ECU. What is it, for sure understood. For what purposes it is necessary for the car - too. Try to monitor the condition of not only the electronic unit, but also sensors and actuators. They should be in perfect condition so that there is no problem.