Car diagnostics via laptop: how to do everything correctly yourself?

Author: Ivan Baranov

All modern vehicles are equipped with various electronic systems. Sometimes it is simply impossible to identify a malfunction of a particular component without a thorough check of the car. From this material you will learn how to diagnose a car using a laptop with your own hands, what is needed for this and how to do everything correctly.

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Why is computer diagnostics of a car necessary?

If you decide to perform diagnostics using an adapter, you will probably be interested in knowing what this procedure will do. First of all, this is an opportunity to save money and time. Especially if auto diagnostics are carried out at the moment when the car began to behave incorrectly - by checking all working systems, you can obtain information about their condition.

Checking vehicle components

All you need to do is simply connect the computer to the diagnostic connector and watch the operation of the main parameters. If there are deviations in the operation of certain systems and components, the problem is solved either independently or with the help of specialists. If, for example, engine diagnostics are entrusted to specialists, it is quite possible that they will simply take money from the driver, keeping the car for several days at the station in an attempt to find a fault.

If you carry out self-diagnosis of the car, then the whole procedure will be faster and easier. The driver has an excellent opportunity to identify the problem with his own hands, or at least its direction, and only then find one or another specialist. If you try to find a qualified professional at a service station initially, it may take time. Moreover, this specialist must understand computer diagnostics, and today there are not many such people.

Of course, learning all the intricacies of checking a vehicle is not a particularly simple process and will take time. In order to accurately know the picture of the state of nodes and systems, you need to be able to decipher the combinations of errors that will be received in the process (video author - Evgeniy Gordienko).

Description of the OBD2 standard at the diagnostic connector level

Attempts to automate diagnostic tools have been made since the advent of on-board computers in the mid-70s. Strictly speaking, it was difficult to call these devices computers; this term appeared much later. Electronic control units for the operation of power units already had primitive means of self-diagnosis, but they could only be used by specialists by closing certain contacts of the ECU connector. The need to unify the exchange of data between automotive peripherals and the control unit was discussed in the early 80s, and it was then that the first attempt was made to implement this idea. General Motors specialists developed a data exchange protocol using the proprietary ALDL interface, which was initially used only on cars of this brand. After improvements to the protocol in 1986, aimed at increasing the speed and volume of data exchange, other automakers drew attention to it, and in 1991 in California, where environmentalists began to sound the alarm due to air pollution, a regulation was introduced according to which all products sold in In this state, cars were required to use the OBD1 protocol.

Although the original focus of the standard was environmental (emissions monitoring), it was greeted with enthusiasm by service center specialists. But only five years later a second version of the protocol appeared, in which error protocols, the connectors used, and the location of the connector were already regulated and standardized. The standard was extended to all vehicles sold in the United States, so European and Asian automakers wishing to sell their products in North America were also forced to adopt the OBD2 protocol. In 2004, when the standard extended to diesel cars, the protocol was supplemented with Controller Area Network specifications aimed at standardizing the information exchange bus.

How does it all work?

So how does it all work? Special software for diagnosing a car, be it transmission, internal combustion engine or electrical, sends an impulse through the COM port to the tester, as well as to the car controller. The controller also sends a response pulse. The utility receives it, processes it, and then displays the results on the computer display.

The data exchange procedure is carried out according to a specific protocol. Each individual car manufacturer may have its own protocol. But, as a rule, in most cases, diagnostics of car electrical systems and other components are carried out using the ODB-2 protocol. This protocol has several disadvantages. Firstly, it is not supported by all vehicles, and secondly, it has limited capabilities in general.

It must be taken into account that software usually operates with one or another protocol or certain varieties. For example, the VAG-COM program can be used to check vehicles of the VAG company, which produces Audi, Volkswagen, Seat, and Skoda cars. This utility does not allow you to get rid of the error; with its help you can only see some of the parameters that will be displayed.

Diagnostic connector pin designation

Procedure for self-diagnosis

1. Turn on your laptop, tablet or smartphone with the autodiagnostic program installed on it in advance.
2. Find the diagnostic connector we need in the car. Typically, this connector is located somewhere near the steering column. Sometimes it hides in the dashboard, and in older cars it can even be found under the hood.
3. Without starting the engine, insert the scanner and wait for the connection LED to light up. Turn on the ignition only when all settings have been completed for both the scanner and the laptop.
4. Activate the Bluetooth function on your smartphone (other device) and pair the devices. You can understand that the process has started safely and everything is ready for work when the adapter signals with an LED indicator.
5. Launch the diagnostic program, connect the information data stream from the vehicle’s on-board computer. The diagnostician should report that the car computer has been detected and begin processing the incoming data. The program will then display key parameters on the screen.
6. Give the program commands to check various parameters by selecting the desired icons. The data will begin to display on the computer screen. Next, the software will display error codes detected during operation. They can be immediately decrypted online if there is an Internet connection. You can also copy and write down so that you can later refer to error transcripts, databases of which are always easily accessible on the Internet.
7. Error codes should not be deleted immediately, but saved in a file so that they can later be decrypted using Internet databases and calmly analyzed.

Self-diagnosis guide

How to diagnose auto electrics or other components and assemblies? What devices and parameters to use, how to connect a car scanner to the diagnostic connector using a cable, what is the diagram?

What is necessary?

In order for your DIY car diagnostics to be successful, you will need to prepare several basic components. First of all, this is a special car adapter. This device is a special circuit fixed in a plastic case. The adapter is connected via wires to the computer, as well as to the diagnostic output of the vehicle.

Today there are a huge number of options and adapter manufacturers. Regardless of the type and manufacturer, the main purpose of the device is to receive, analyze and transmit information from the vehicle test connector to the computer.

Scanner for car diagnostics

As for the computer, it does not have to be the most modern - to carry out diagnostics, a regular PC with minimal parameters will be enough. The most compact option would be a laptop. If necessary, you can even use a pocket computer, but this will require an additional connector. As for directly choosing a PC, everyone decides for themselves.

The main requirement for diagnosing and identifying faults is the convenience of the procedure. But always remember that it is not practical to use a cable that is too long for a connection, the length of which will be more than five meters, as the signal may be lost.

In addition, there may be a need to remove basic parameters from the vehicle while driving. In this case, the most optimal option would be to use a laptop. If you need to test and appreciate the most important functions, car dynamics are not necessary. In principle, most of the procedures are carried out at idle speed; moreover, sometimes it happens that you don’t even need to start the engine to check.

If you plan to regularly carry out diagnostic procedures using a laptop in the future, it may be important to purchase a used computer and use it for this purpose. Moreover, you don’t need a powerful and modern device - the main thing is that it is equipped with a COM port, but if it is not there, then the problem can be solved by purchasing an adapter.

Deciphering error codes

One of the main advantages of the OBD2 protocol is the unification of fault coding, which guarantees the same interpretation regardless of the make/model of the vehicle. The structure of the fault code is shown in the following figure:

As a rule, when the scanner displays detected errors, it also indicates a description of the malfunction along with the code. And based on the code and description of the error, you can try to search the Internet for ways to troubleshoot the problem by entering the error code and the name of your car into a search engine. Car service workers are generally well aware of what each error means and what needs to be done to correct it. But car enthusiasts should be careful: information gleaned from specialized forums and other automotive resources may contain errors or inaccuracies that may affect the results of self-repair, so the best way to solve the problem is to search and watch relevant videos.

Video “Step-by-step instructions for checking a car”

Detailed and visual diagnostic instructions are given in the video below (the author of the video is VD Test).

All modern vehicles are equipped with various electronic systems. Sometimes it is simply impossible to identify a malfunction of a particular component without a thorough check of the car. From this material you will learn how to diagnose a car using a laptop with your own hands, what is needed for this and how to do everything correctly.

In what cases does a car need diagnostics via a laptop?

Before you diagnose a vehicle using a laptop, you need to understand why it is needed. Diagnostics is a procedure during which error codes are read on various components of the vehicle. Thanks to modern software and high-tech equipment, it is possible to diagnose even small changes in the operation of various injector systems, chassis or transmission. And this is quite possible to do on your own.

Computer check of car systems

Today, do-it-yourself computer diagnostics of a car is often carried out by car enthusiasts in order to reconfigure the control unit. This is done in order to improve the operation of various units and mechanisms of the vehicle.

Thanks to the use of modern software and additional plugins, a car enthusiast can:

• change (decrease or increase) the number of idle speeds;
• change lambda characteristics, that is, adjust the fuel supply;
• if plugins are available, you can program the car electronics interface;
• set up automatic testing in case of malfunctions or deviations in the operation of systems.

So when do you need to independently diagnose an injector or other systems via a laptop?

1. First of all, this is done when sensors on the dashboard signal the motorist about the presence of possible malfunctions.
2. Motorists also often carry out this procedure when incorrect operation of various mechanisms and components is detected. You can check the car in order to understand whether they are really faulty.
3. Recently, diagnostics of the injector, chassis and transmission have become increasingly common when purchasing a used car.
4. In order to reduce possible vehicle repair costs. This is called preventive diagnostics using a laptop, and experts recommend performing it at least once a year. By learning in advance about the problems that exist in the components of the car, you can save a lot of money.

When is electronic testing necessary?

Computer diagnostics is not a mandatory procedure, but in certain moments it is the best and only way to solve all the problems in the car. Although there are circumstances when it is advisable for a car owner to seek this service.

The machine has one or more signs of malfunction

If a light comes on on the car’s dashboard indicating a particular malfunction, or the performance characteristics of the car itself have noticeably deteriorated, experts advise doing electronic diagnostics of the element whose failure is indicated by the system (assumed by the driver). Timely testing will allow you to insure against the further development of existing faults, preventing their manifestation during travel. In addition, eliminating failures in the early stages will cost much less.

Long journey expected

When going on a long trip (especially to an unfamiliar place), it is advisable to go for preventive diagnostics. Based on the test results, you can find out which parts are best changed before traveling, and also identify possible faults that have not yet manifested themselves in order to stop their further development. This way, the motorist will be able to save time looking for a service in an unfamiliar place, which, by the way, may not come across at all on the way.

Buying a used car

When choosing a used car, it is better not to be lazy and spare money on computer diagnostics. Sellers of old cars are often in no hurry to report all existing faults (especially if they cannot be determined visually). This is guaranteed to protect you from buying a bad car. Using special equipment, a specialist will analyze and check all elements of the car, warning you about any problems. Testing allows you to determine with the highest accuracy whether the car has been involved in an accident, whether there are any malfunctions and a predisposition to their occurrence.

Preventive measure

Computer testing is an optional event. But experts recommend that you systematically go through it even though the car is in perfect condition. During the testing process, weaknesses are usually identified that do not show themselves, but create risks of emergency situations. By coming for diagnostics once every 6 months, a motorist significantly increases the level of vehicle reliability.

Source

Necessary tools and devices for diagnostics

In order for computer diagnostics of a car to give results with your own hands, you need to properly prepare for it. Today there are a huge variety of devices for testing automotive systems. This is due to the fact that every modern vehicle is computerized and sooner or later it will need diagnostics. The owner of any car needs to know where the diagnostic connector is located; usually it is located under the dashboard near the steering wheel (video author - al zh).

It is better to use a scanner for testing. This device is necessary in order to communicate directly with the control unit, as well as read error combinations. Using a scanner, you can take all the necessary readings from sensors, as well as vehicle control systems. Thanks to the scanner, you can diagnose the performance of the executive units. It is imperative to find a scanner, since no system can test itself with complete accuracy.

Please note that each vehicle requires a special adapter. You can purchase a universal device that can be used for different brands of cars.

If you don’t have a scanner, then you can do without it, what you will need:

1. Laptop or computer. With a home PC it will be a little more difficult. In any case, the main device is a computer, but you can also test the car using a smartphone.
2. Adapter, which is required to connect to the diagnostic connector. You will need a specific adapter specifically for your car or a universal device. For example, devices from the K-Line company are popular with our car enthusiasts, since they allow you to connect to most domestic and imported cars. The adapter must come with a special wire or cord to synchronize the laptop and adapter. If there is no cord, it is impossible to connect the PC.
3. Software . You can find many different programs on the Internet. Some of them are focused on specific vehicle models, others are universal. It is advisable to select software for a specific car brand, since they are initially programmed to work with a specific on-board computer.

ELM327 programs for iPhone and iPad (iOS)

Below are elm327 programs for use on iPhone and iPad, i.e. on smartphones and tablets with the iOS operating system. There are quite a few programs for these devices and, as a rule, they are all in English. But we still tried to choose good programs for you that are easy to learn and have a wide range of functions. Please note that Apple devices only support Wi-Fi adapters, so the programs do too.

DashCommand

A fairly good, with all the necessary features, elm327 program for iPhone and iPad. It is universal and suitable for diagnosing a huge number of cars. Easy to learn and intuitive despite the lack of Russian language.

Works with adapters: Wi-Fi

Download DashCommand for iOS

OBD Car Doctor

A simple and convenient program in Russian. Allows you to read engine operating parameters, and it is also possible to read and erase engine check errors.

Works with adapters: Wi-Fi

Download the OBD Car Doctor program for iOS

Devices and software

Wifi or bluetooth adapters

Such adapters can be connected without a cord, since they are designed to interact with a PC or mobile phone. Thanks to the adapter, you can not only diagnose the vehicle, but also monitor the operation of all electronic parameters while driving.

The operation of such a device is quite simple. The gadget connects to the vehicle's diagnostic connector. Then it must be synchronized with a computer or smartphone using a Wi-Fi network or Bluetooth connection. After synchronization, the software starts on the computer, further actions are carried out in accordance with the instructions (the author of the video is Pro Polo).

Currently, the automotive market offers a huge range of adapters. In terms of price and quality, ranging from Chinese devices to originals. When purchasing an adapter, you need to select it specifically for your car model, this way you can get more accurate results during the test.

Using Android

In general, there are enough programs for diagnosing a car using a mobile device running on the Android platform, so you won’t have any problems with the choice. As practice shows, most of our motorists use the Torque Pro utility. Based on reviews, it can be judged that it gives the most accurate results when scanning systems.

As for the functionality of this software, it is quite broad:

• demonstration of car parameters in real time;
• full testing of all systems;
• using a GPS tracker to remember what actions you have already performed, etc.

In addition, the software is characterized by a convenient and understandable interface for any user.

Via Windows Mobile or Java

In this case, the most popular application is Check-Engine. In addition to the main functionality, this program immediately offers not only to count, but also to decipher combinations of faults. When the errors are corrected, the utility will allow you to delete them from the control unit’s memory. In addition, the program will even give hints to the user, if necessary, it will be possible to save the report. If necessary, all error codes can be generated into one SMS message to be sent to a specialist.

TOP Android applications for car diagnostics

Well, we come to the most interesting part - a review of the best programs for car diagnostics on Android.

Carista Obd2

The application has been operating since 2013, the last update in the Play Market was released on June 30, 2022. There is a paid version with extended functionality (1 week - $10, 1 year - $40). The developer company has its own adapter - if you buy it, a month of using the Pro version is free.

According to users, this is one of the best applications for diagnosing a car on Android, even at the level of free functionality (basic engine check, gas distribution system, exhaust toxicity analysis). Advanced scanning (no worse than in a service center) allows you to test all modules of the car - anti-lock braking system, brake system, airbags, tire pressure sensors, etc.

The program also provides additional functionality - personalizing settings, unlocking hidden functions, etc.

Hob Drive

Second place in our ranking of the best car diagnostic programs for Android goes to the Hob Drive client. The application is a triple service - an on-board computer, a gasoline consumption analyzer and a diagnostic tool via OBD2/ELM327.

Both paid and free versions are available on the Play Market. The latter allows you to perform ongoing diagnostics of vehicle errors, the former provides constant monitoring and prompt notification, as well as monitoring overheating and suspicious lags.

The on-board computer records fuel consumption and performs power measurements. The program has a built-in trip planning option - estimating driving time on the remaining tank, refueling records, route statistics, and cost calculations. The interface can be customized according to your preferences; there are many built-in themes.

InCar Doc

An Android application that performs full launch car diagnostics for a scanner with an elm327/OBD2 processor.

Performs a full scan of the vehicle, with diagnostics, monitoring and statistics logging. Recognizes the cause of the Check Engine light, deciphers error codes, and clears old codes.

There is a paid version with extended functionality. It works in real time - analyzes engine parameters, fuel consumption, records gas stations, shops, services, remembers the location of the car, etc.

Know-how of modern computer diagnostics

This is accessibility, the ability to diagnose the car yourself.

Currently, scanning for flaws in the functioning of a car can be easily done in a garage before a serious flight or simply an emergency stop on the side of the road. For example, if the “check engine” window lights up on the instrument panel.

Special equipment is not required. To identify the cause of the problem, only certain skills are required, as well as:

1. vehicle,
2. laptop,
3. adapter,
4. cable for connecting via a computer adapter to the vehicle controller.

Necessary equipment for engine diagnostics

To successfully diagnose a car via a laptop, you need to comply with some requirements. There are many testing devices today. Specialized software is produced for each make and model of car. Although, there are software and adapters that are suitable for various brands of cars.

First of all, the driver needs to find the place where the diagnostic device (scanner) is connected. This could be under the glove compartment, near the steering wheel, etc. Today you can buy a scanner inexpensively. The scanner connects to the control unit through a connector and reads various combinations of errors. The scanner makes it possible to obtain complete information from sensors and vehicle control systems. The scanning device will analyze the performance of all critical components of the car structure.

Before purchasing a scanner, be sure to make sure that it fits the required make and model of car. Of course, it will not show the oil level in the engine and in the box, and will not check the ball joint, but it will provide information on many other parameters.

If you don't have a scanner

If there is no scanner for car diagnostics, then you can carry out troubleshooting work without it. For this you need:

1. Laptop or computer.

2. Adapter. It connects to the diagnostic connector. Also purchased depending on the make and model of the car. One of the most common adapters is the K-Line adapter. It is suitable for many makes and models of passenger vehicles. The adapter comes with a cord for connecting the connector of the machine and laptop, and a CD with software.

3. Software. There are also many diagnostic programs, as well as devices. There are universal programs with which you can do do-it-yourself diagnostics of cars of different brands (domestic and imported). There are programs only for a specific machine.

Software for car diagnostic devices

Wifi and bluetooth devices

The advantages of working with such adapters are the ability to synchronize with the car wirelessly. Convenient to diagnose while driving.

Working with such wireless devices is not difficult:

1. Insert into the connector in the car to connect the scanner.
2. Turn on Wi-Fi or Bluetooth on the device you want to connect (laptop, tablet, phone).
3. After connecting the car and the device, run the diagnostic program.

One of the most common scanner-adapters is the ELM 327 scanner. It can also be easily ordered from Aliexpress. The main thing is, before purchasing, look at the list of which cars they can diagnose.

Devices running the Android operating system (Android

For devices with the Android operating system, you will need to install applications for car diagnostics. According to reviews and comments, the Torque Pro application is installed the most. Reviews often say that this application provides accurate data.

Torque Pro functionality:

• the parameters of the scanned vehicle are immediately visible on the screen;
• diagnostics occurs completely;
• The GPS track allows you to record actions, which is very convenient (allows you to see what was scanned before).

The program interface is clear and convenient even for a beginner.

Devices running the Windows Mobile (Windows Mobile) or Java operating system (Java)

For tablets and phones with Windows and Java operating systems, the most recommended application is Check-Engine.

This application not only reads the errors found, but also deciphers these error codes.

After correcting the errors, the Check Engine utility will erase old errors from the control unit’s memory. To save and generate a report, the application shows tips on how to make a report and send an SMS to a specialist.

Adapter

On currently produced VAZ models, there is a high demand for adapters (level converters) of the KL series with a USB connector. They are designed for docking a laptop (or desktop personal computer) with channels “K” or “L” of the ECU (electronic control unit).

The adapter is used to diagnose vehicles and control their functions. Before starting work, you must install the appropriate diagnostic programs (“software”) and a driver for adapting the programs to your computer.

It is better to buy an adapter for diagnostics in the form of an already mounted unit with a USB port for a computer.

Adapter models:

Almost all adapters support domestic cars produced since 1998. The range of models is large. The choice depends only on your preferences in technology and income.

The cheapest adapter for VAZ is ELM327. The most commonly used universal adapter is BM9213.

ELM 327

Adapter design:

• printed circuit board (material: foil-coated fiberglass),
• OBD II standard port for connecting a USB cable inside the car,
• body (material - metal or plastic).

OBD II

Technical data:

Voltage - 12 V (you can connect a laptop from the cigarette lighter). Current - 10 mA. Voltage stabilizer for K-line - 5 V and 12 V. ECU - VAZ models "January-4", "January-5".

The interface for K-line is ISO-9141. The interface for L-line is ALDL.

The adapter can also be connected to the “L-line” of the ECU of foreign cars.

Programs for ELM327 for Android

Many programs for ELM327 scanners are distributed in two versions: free and advanced, professional (Pro). There are applications that claim to be free, but require payment for some additional features. There are also professional products that allow the use of a greatly reduced demo version to familiarize yourself with the functionality. Most scanner programs for Android support communication with mobile devices via Wi-Fi and Bluetooth.

Torque

One of the most popular programs for ELM327 scanners. There is a Russian version of the interface with minor inaccuracies and translation flaws. There are two software options available to users. One is completely free (Lite). The second (Pro) has advanced functionality and costs 165 rubles.

Even the free version has very good features. These include the following functions:

• Check-Engine error detection;
• resetting fault codes and storing them in a log;
• displaying information from oxygen sensors;
• fuel consumption accounting;
• monitoring of a number of parameters with display of indicators on the desktop;
• informing about the achievement of critically harmful/dangerous parameter values;
• ability to select parameters for tracking;
• customizing panels on the desktop;
• recording geolocation data.

The basic version has good functionality for diagnosing basic vehicle systems, monitoring important parameters while driving, and eliminating some errors. The Pro version is characterized by expanded functionality for diagnosing and correcting errors, including deciphering codes.

OpenDiag Mobile

The program was developed by Russian specialists and is intended to work with domestic fuel-injected cars. Among the advantages are an authentic Russian interface and a good set of free functions, as well as the ability to communicate via a USB cable (in addition to Wi-Fi and Bluetooth).

The application provides diagnostics of the following units and systems:

• engine control (Bosch, Itelma, January, EMS, Mikas);
• anti-theft APS systems, immobilizers;
• electrical package modules (Priora, Kalina, Granta, Vesta);
• electric power steering (KEMZ, Autoelectronics, Mando, etc.);
• airbags;
• anti-lock braking system;
• heater and climate control;
• windshield wiper control unit.

The program allows you to determine the amount of fuel required for a trip, displays information about the temperature of the coolant, air, fuel pressure, etc. All information is displayed in Russian. Users who download the free application can purchase additional paid blocks if necessary.

Programs for diagnosing VAZ cars

Due to the fact that there are many of them, let’s name a few of the most common and advanced:

1. KWR_D is one of the most reliable. Its advantage is that there are many useful adjustments. We list the main functions: - control of mechanisms (nozzles, coils, fans, etc.), - monitoring of vehicle parameters.
2. ICD 1.2.0.1 is the same (the program is free).
3. Diagnostic Tool vl.31.2 - control functions, there are adjustments.
4. AVTOVAZ NEW is the most modern option. The advantages are immobilizer control and adjustments.
5. Sens Diag - comprehensive diagnostics.
6. Motor tester is the same.
7. My Tester VAZ is the same with direct adaptation to VAZ models.

All of these programs work with Bosch blocks.

How to diagnose a VAZ car using a laptop:

1. Complete diagnostic equipment (laptop, connection cable, adapter),
2. Install the appropriate program and drivers on the laptop,
3. Using a cable, create a logistics chain “laptop - adapter - ECU - car computer”,
4. Setting up a connection between a laptop and a car computer,
5. Turning on the engine
6. Diagnostics.

What is needed to diagnose the ECU using a laptop

The correctness of checking a car in this way depends on the preparatory work and the availability of all the required equipment. Many devices are now offered for testing machines. It is recommended that the car enthusiast install the diagnostic connector in advance (it is worth carefully looking at the places near the steering wheel - where it is usually located), and then purchase the necessary equipment .

The main devices are:

• Laptop or smartphone . The phone is convenient for checking a car with your own hands while on the road, if it suddenly stalls in the middle of the road, and the path to the final destination is not close. A laptop, just like a desktop computer, will allow you to conduct more serious diagnostics. Subsequently, it will be possible to install professional diagnostic software under it. It is allowed to use the most ordinary laptop with a standard RS-232 connector intended for a data cable, and at least one of the wireless access units must be installed in it. It would be better if it were Bluetooth , and although it is not as fast as Wi-Fi , most adapters (scanners) work on it. If you use a desktop computer, you won’t be able to check the car on the road, but such a device is more powerful. If it is old and does not have a Bluetooth connector, then adapters or wireless modules can save the situation.
• Scanner. It connects to the diagnostic connector; you will need to select it specifically for your car brand. Some adapter manufacturers create such a device that can be connected to most models of imported and domestic cars. A cord must be supplied with the adapter that will connect to the PC. The scanner contains connector blocks, a chip circuit, a control and signal panel. It serves as a transmission link between the on-board computer and the laptop, on which the received information is processed into a readable form.
• Software . It can be downloaded directly from the Internet, where there are many programs. They can be either universal or for a specific model. It is still advisable to choose a program for a specific brand; it will be “tailored” for a specific model.

Types of adapters for OBD2

They can be professional, dealer and amateur . There are universal options, as well as those designed for a specific model. The best option is multi-brand scanners that can work with different cars.

• Dealerships . These are expensive scanners that are offered in auto centers ; they include professional devices created for a specific brand of car. They can even be used for trucks.
• Multibrand . They are multifunctional and can be used for many models. They are used in car services, and they can also be used by advanced users who understand not only cars, but also software. With the help of such adapters, DTC faults can be detected and they can pinpoint the location of the faulty component or spare part. Multi-brand adapters can connect to PCs and smartphones, most of which have a display for easy use.
• Hobbyist models can monitor sensors and recognize basic fault codes. Such car scanners are mainly used by novice car enthusiasts . Using them, you can identify an open circuit or failure of the sensor, after replacing which the electronics operate in normal mode. It is within the power of amateur sensors to remove an identified error when the “Check Engine” button lights up. Devices of this group are based on the ELM327 chip . Its relationship with the car’s electronics is supported using AT commands, the exchange of messages in them is organized using the RS-232 protocol . The connection to a computer can be via Bluetooth, USB or Wi-Fi , carried out using the UART .

Scanners not only read errors, they also delete them and help view all data from the on-board PC. Adapters and connectors for them are selected for a specific car brand.

What adapters are currently on the market?

Most often, to diagnose a car via a laptop with your own hands, scanner models based on the ELM 327 chip are used. Their wireless variations can be an excellent purchase.

Among amateur adapters , “Scan Tool Pro” the manufacturer has endowed it with advanced functions; in addition to standard functions, they can read and restart the brake system, as well as airbags. With their help, you can scan the performance characteristics of the car itself and its sensors. After errors are identified, the device updates itself, but with the amendments made; it is noteworthy that it can do all this even while the car is moving. Scan Tool Pro can accurately determine the VIN of a vehicle, transmission or engine.

Among the multi-brand models that help you carry out DIY diagnostics, the “Smart Scan Tool” deserves special attention; it has an ELM323/327 chip circuit installed. He is able to diagnose all modern cars that are less than 20 years old. Using it, you can carry out diagnostics from all installed sensors in real time, and then, based on the data received, customize the car for yourself. In addition, you can trust the diagnostics to the Chinese device Delphi DS150 and Autocom CDP .

Portable scanners include Launch Creader V , a compact and convenient diagnostic tool. An excellent professional device is Autel MaxiSYS , it has a Russian-language interface.

Dealer include inventions from BOSCH - a professional device, as well as Bluetooth Newest MB Star C4 Scanner Tool - designed specifically for Mercedes.

Pinout of OBD-2 connector and analogues

Programs for car diagnostics using a laptop

When purchasing an adapter, software is included with it. If an application for self-diagnosis of a car is not available or for some reason does not suit the car owner, then he can independently download the program he likes from the Internet.

The main functionality of the program is:

• deciphering the received error codes;
• determining and displaying on the laptop monitor the basic operating conditions of car systems;
• determination and interpretation of the status of identified deviations;
• eliminating the causes of errors and erasing them from the system memory;
• maintaining reporting documentation on identified faults and ongoing maintenance.

Popular programs include :

• Motor-Tester is a professional program designed for diagnosing domestic cars, such as UAZ, VAZ, GAZ and similar;
• Uniscan is a universal version of software used to monitor deviations in the electronic systems of many foreign cars, the year of manufacture of which does not exceed 17 years.
• KWR-D - the program is reliable and equipped with many useful adjustments. With its help, you can monitor important parameters of the vehicle, as well as check various mechanisms, such as coils, injectors and others.
• Vagcom - software for VAG group cars, copes well with faults on Volkswagen, Audi, Skoda, Seat and others.

Diagnostic parameters for VAZ injection engines

What to pay attention to:

1. With the engine turned off, temperature sensors (data correctness); - throttle valve (presence of wear of the throttle mechanism; maximum wear - no more than 2%); — oxygen sensor (ADC MAF); presence of channel wear; maximum wear - no more than 1,035 V;
2. With the engine running and warmed up to normal (idling speed), the following parameters are checked (the value in each specific case depends on the engine model and ECU): - revolutions per minute; — air consumption for an 8 valve engine; — air consumption for a 16 valve engine; — injection time; if necessary, injection correction; — correction factor (%); — multiplicative component of correction; — additive component of correction; — cyclic air consumption (mg/stroke) for an 8-valve engine and for a 16-valve engine.
3. Screenshots of engine diagnostics on the monitor (depending on the ECU model using the example of a VAZ 2107) - ECU “January 5” - ECU M73

ELMScan Toyota

If you own a Toyota or Lexus, ELMScan Toyota is a good OBD2 program in Russian. Despite the fact that the program was created specifically for the above-mentioned cars, it is also compatible with cars of other brands that have a suitable connector for connecting diagnostics. It is offered in two versions: paid and free, it has an intuitive interface, but although it is completely Russified, English terms are still found in it here and there.

ELMScan Toyota is included in the list of the best programs for obd2 diagnostics, thanks to its capabilities:

1. Reading complete information about the vehicle (model, engine size and name, VIN code and calibration id).
2. Determining errors in sensor operation.
3. Clearing fault codes.
4. Determination of motor operating parameters in real time.
5. Perform all active tests of vehicle electronic system components.
6. Display data in the form of numbers and graphs.
7. Reset ECU parameters.
8. Storing a database of fault codes.

This one of the best programs for OBD2 on Android will reveal all the secrets of the engine, transmission, cruise control, immobilizer, auxiliary security systems, suspension, electric power steering, and other vehicle sensors.

Important: in the free version of the program, support for many sensors is disabled, so for diagnostic efficiency, it is recommended to immediately purchase the full package of functions.

Objective indicators

Factors that determine the correctness of the data:

• car (engine) model,
• laptop (scanner) and adapter model,
• engine temperature,
• ambient temperature,
• operator qualification.

Thus, it is clear that the conclusions when diagnosing a particular car may not always be completely adequate to the current technical situation.

Although you can get an idea of ​​the malfunction and the cost of repairs.

OBD2 connector pinout

As already noted, the standard provides for the use of a trapezoidal connector with 16 pins, almost half of which are reserved for independent use by automakers. The contact diagram (pinout of the OBD2 connector) is shown in the following figure:

Contact assignment:

1. reserved for automakers;
2. SAE-J1850/1850 (+);
3. reserved for automakers;
4. grounding of the car body (ground);
5. signal ground;
6. high-speed CAN bus;
7. bidirectional K-Line bus;
8. reserved for automakers;
9. low-speed CAN bus;
10. SAE-J1850/1850 (-);
11. reserved for automakers;
12. reserved for automakers;
13. reserved for automakers;
14. high-speed CAN bus;
15. L-Line standard bus;
16. positive power contact from the battery.

Since the most common data exchange protocols in a car are CAN/K-Line/L-Line, these contacts are used in most cases. The interaction scheme between the ECU and the monitored units is as follows: the on-board computer sends signals to sensors and actuators via the specified buses in accordance with the OBD2 protocol, receiving from them data on malfunctions and deviations in operation in encoded form (again in full compliance with the standard). Auto scanners interrogate the ECU, receiving and decoding this data, displaying it on the built-in display or external device. The presence of reserved buses requires the connection of external devices, the diagnosis of which is not provided for by the standard. Quite often, it is precisely such devices that cause the auto scanner to not work.

Since the main bus is CAN, it is usually its break or short circuit that causes the lack of communication between the diagnostic device and control units (for example, ABS, body elements, airbags). Their incorrect connection can cause a short circuit in the CAN bus. The problem is solved by turning off these devices one by one. It’s rare, but it happens that a car has a non-standard car radio (or media center) that shorts out another popular bus - the K-Line. Check this in the same way by turning off the radio. However, the pinout of the OBD2 diagnostic connector, made at the factory, should not lead to such problems, regardless of the number of additional devices, the diagnosis of which is not provided for by the basic part of the protocol. But independently connecting any non-standard device can cause diagnostic equipment to malfunction.