Universal USB adapter K-L line BM9213 for tuning a fuel-injected car engine. Adapters K-L-LINE K line adapter pinout

It's probably happened to all of us: you're driving in your car and suddenly the yellow "Check Engine" light illuminates on the dashboard as an alarming warning that there's some kind of engine problem. Unfortunately, this in itself does not give any hints as to what exactly is causing the problem and could mean anything from a loose gas cap to problems with the catalytic converter. I remember the '94 Honda Integra had an ECU under the driver's seat and the red LED would flash if there was any problem with the engine.

By counting the number of “blinks”, it was possible to determine the error code. As vehicle ECUs become more and more complex, the number of error codes increases exponentially. Using On-Board Diagnostic (OBD-II) can solve this problem. This adapter allows you to use a personal computer for OBD diagnostics. The AllPro adapter is functionally compatible with ELM327 and supports all existing OBD-II data exchange protocols:

ISO 9141-2
ISO 14230-4 (KWP2000)
SAE PWM J1850 (Pulse Width Modulation)
SAE VPW J1850 (Variable Pulse Width)
ISO 15765-4 Controlled Area Network (CAN)

VPW, PWM and CAN
The first two ISO protocols are described in the previous publication mentioned above. A detailed description of OBD protocols is beyond the scope of this article; I will just briefly list them. J1850 VPW (Variable Pulse Width) is a protocol for General Motors cars and some Chrysler models with a transmission speed of 10.4 kbit/s over one wire.

The voltage on the VPW bus varies from 0 to 8 V, data is transmitted along the bus by alternating short (64 μs) and long (128 μs) pulses. The actual data transfer rate on the bus varies depending on the data bit mask and ranges from 976 to 1953 bytes/s. This is the slowest of the OBD protocols.

J1850 PWM(Pulse With Modulation) is used in Ford vehicles. The transmission speed here is 41.6 kbit/s using a differential signal over two wires. The bus voltage varies from 0 to 5 V, and the pulse duration is 24 μs. Working with this protocol requires careful programming of the microprocessor, since the speed of execution of C language instructions on a PIC microprocessor, even with an improved PIC18 architecture, becomes comparable to the length of a short PWM protocol message (7 μs).

CAN(Controlled Area Network) protocol was developed by Robert Bosch in 1983 and was finally standardized in ISO 11898. The use of a CAN data bus in a car allows various devices to communicate with each other without going through the central processor, the so-called multi-master mode.

The advantages are also increased transmission speed, up to 1 Mbit/s, and better noise immunity. The protocol was originally intended for use in cars, but is now being used in other areas. To increase the reliability of data transmission, CAN buses use a method of differential signal transmission over two wires. The wires that form this pair are called CAN_High and CAN_Low.

In the initial state of the bus, both wires maintain a constant voltage at a certain base level, approximately 2.5 V, called the recessive state. When transitioning to the active (dominant) state, the voltage on the CAN_High wire increases, and on the CAN_Low wire decreases, Fig. 1.

There are also two message or frame formats - standard with an 11-bit address field (CAN 2.0A) and extended with a 29-bit address field (CAN 2.0B). The ISO 15765-4 standard specifies the use of both CAN 2.0A and CAN 2.0B for OBD purposes. Together with the bus transfer rates of 250 and 500 kbit/s, this creates 4 different CAN protocols.

Does your vehicle support OBD-II?
OBD is only mandatory in North America and Europe. If in America this rule has been in effect since 1996, the European Union adopted the EOBD version of auto diagnostics, based on OBD-II, relatively recently. In Europe, OBD became mandatory starting in 2001, and even for diesel engines in 2004. If your car was manufactured before 2001, it may not support OBD at all, even if it has the appropriate connector.

For example, the 1999 Renault Kangoo does not support EOBD (although the 2004 editorial Kangoo dcI60 with CAN protocol was successfully paired with the described adapter, and the Renault Twingo does! The same cars made for other markets, such as Turkey, may also not be compatible with OBD protocol How to determine which protocol is supported by the car's electronic control unit?

First- You can search for information on the Internet, although there is a lot of inaccurate and unverified information there. In addition, many vehicles are produced for different markets with different diagnostic protocols. Second a more reliable way is to find the connector and see what contacts are present in it. The connector is usually located under the dashboard on the driver's side. The ISO 914-2 or ISO 14230-4 protocol is defined by the presence of pin 7, as shown in Table 1.

Most cars of recent years of production only support the CAN protocol with pins 6 and 14, respectively. In Europe and North America, all new cars from 2007/2008 onwards must use CAN-based OBD only. I note, however, that, as correctly noted in the comment, “If the brand is present in the table, this does not guarantee OBD-II support.”

Use of L-line in ISO 9141/14230… I would also like to say something about the L-line in ISO 9141-2/14230-4 protocols. Nowadays it is practically not used anywhere, since only the K-line is sufficient for the communication initialization procedure. The standard, however, states that the initialization signal must be transmitted along two lines simultaneously, K and L. Vladimir Gursky from www.wgsoft.de, author of the ScanMaster ELM program, has collected a large collection of various ECUs.

As an example of the need for an L-line, he cites the 2005 Renault Twingo 1.2L. Using only the K-line here when initializing results in an incorrect motor address in the ECU responses. If initialization is carried out by K and L simultaneously, then everything works correctly.

Fig 2

AllPro adapter to PIC18F2455
The diagram of my all-protocol OBD-II adapter is shown in Fig.2. The basis is a Microchip PIC18F2455 microcontroller with a USB interface module. The device uses a 5V supply voltage from the USB bus. Capacitor C6 serves as a filter for the internal 3.3 V stabilizer to ensure operation of the USB bus. LEDs D2 and D3 are transmit/receive indicators, and LED D1 is used to monitor the status of the USB bus.

The output of the ISO 9141/14230 interface is driven by half of the driver IC2-2, and the input signal is fed through the R12/R13 divider to the RX input (pin 18), which is a Schmidt trigger, like most PIC18F2455 inputs, which provides fairly reliable operation. IC3-1 and R10 are used to control the L line.

The J1850 VPW bus requires an 8V supply voltage from the L78L08 IC4 regulator. The VPW output is supplied through inverter IC3-2 and buffer FET Q1. The R7/R8 divider and the internal Schmidt trigger at the RA1 input make up the J1850 PWM protocol input interface. The internal comparator (inputs RA0 and RA3) PIC18F2455, together with resistors R4, R5, produces a differential PWM signal. IC2-1 and FET Q2 are used to control the output of the PWM bus.

I would also like to say something about CAN support. Microchip does not produce controllers that contain both CAN and USB. You can use a controller with a CAN module and an external USB chip like FT232R. Or vice versa, connect an external CAN controller, as is done in this adapter. The CAN interface here is formed by the MCP2515 controller (IC5) and the MPC2551 transceiver (IC6). The MCP2515 is connected via an SPI bus to the PIC18F2455 and is programmed every time the adapter is powered up.

The RC bus termination chains R14/C10 and R15/C11 are designed to reduce reflections on the CAN bus in accordance with the ISO 15765-4 standard. Their use is not necessary; with a relatively short cable, reflections can be neglected. Instead of PIC18F2455, you can use PIC18F2550 with the same firmware, see replacement options in Table 2.

table 2

The appearance of the device is shown in Fig. 3 and the cover, and the printed circuit board is shown in Fig. 4.

Programming PIC18F2455

To program PIC18 you can use a simple JDM programmer, the diagram is shown in Fig.5.

pic 5

It is very simple and could be assembled in an hour on a breadboard. The disadvantage is that the programmer requires a serial (Com) interface in the computer and does not work with virtual USB/Com adapters. The use of laptops is also not recommended, as they do not provide the required voltage at the Com port output.

Figure 6

The programmer wiring is shown in Fig.6 and is made using the so-called “stripboard” technology, a fairly popular approach to layout. A typical stripboard has a 2.54mm array of holes for mounting electronic components, connected by strips of copper on the back side, hence the name stripboard.

By cutting the strips on the reverse side and installing wire jumpers on top, you can quickly assemble relatively simple structures. The strips are easily cut by countersinking the holes with a regular drill. There is even a special program - “LochMaster” for designing structures in this way. When using the programmer, please note that the personal computer case (pin 5 of the DB9 connector) does not match the programmer case.

Another condition is to use a “complete” serial cable with all the wires necessary for the operation of the circuit. The programmer works reliably with WinPic, the only problem is that you need to separately download the descriptor file PIC18F2455.dev (or PIC18F2550.dev) from the Microchip IDE distribution after WinPic itself is installed.

Another program that works with the JDM programmer is PICPgm, no additional files are required here, although the author should work on the English grammar, Fig. 7. Adapter firmware is available.

OBD-II cable
To connect to the on-board computer, the adapter uses a “standard” DB-9/OBD-II cable. The cable layout is shown in Table 3.

Connecting and testing the device. A correctly assembled adapter does not require any setup and is recognized by Windows as a USB device. The PIC18F2455 microprocessor does not have its own driver and uses the Windows 2000/XP/Vista CDC (Communication Device Class) driver usbser.sys virtual Com port.

Regarding the use of the driver, however, I would like to add that according to information from www.usb.org, bugs in usbser.sys were fixed only starting from Windows XP SP2 and using the adapter with Windows 2000 can be problematic. Once the adapter is recognized as a USB device and the driver is installed, you can begin testing.

To do this, you need to connect a source of stabilized voltage of 12 volts to pins 1 and 9 of connector J2 and connect the adapter to a personal computer via a USB cable. The presence of 8 V voltage is checked at the output of stabilizer IC4. The next step is to launch the Windows HyperTerm application and connect to the adapter's Com port.

The device has a self-diagnosis procedure that checks the signal flow from output to input using all protocols. To do this, use the “AT@3” command, Fig. 8.

Passage is checked using the following circuits:

IC2-1, R4 for negative PWM bus
Q2, D6, R5 for positive PWM bus
IC3-2, IC4, R11, Q1, D5, R7, R8 for VPW
IC2-2, R9, R12, R13 for ISO 9141/14230
MCP2515 controller response via SPI bus

For example, the absence of IC2 will lead to two errors at once, Fig. 9.

The self-diagnosis procedure does not include checking the CAN transceiver MCP2551; here you can simply measure the voltage at pins 6 and 7. It should be within 2.5 V.

Working with the Adapter
The adapter is compatible with the ELM327 command set and can be used with applications that work with the ELM327. I prefer to use “ScanMaster ELM” by Vladimir Gursky, Fig. 10.

ScanTool.net for Windows v1.13
Digimoto
PCMSCAN
EasyObdII Pro
As an example, I’ll give you a situation that happened to a friend’s VW Passat. The “Check Engine” light came on in the car, connecting the ANPro adapter detected error P0118 - “engine coolant temperature circuit high input”, i.e. high signal level from the coolant temperature sensor, fig. eleven . Further investigation revealed a faulty sensor. After replacing the sensor, the error was erased using the “Clear Trouble codes” button, see Fig. 12. The error disappeared and did not appear again, Fig. 13.

The K‑Line adapter is a data transmission device over a single-wire line, i.e. requests from diagnostic equipment and ECM responses are transmitted over one line. The COM port of the computer has separate inputs for receiving and sending data, and a COM signal adapter is designed for coordination<->K-Line.

The K-line of automotive diagnostics has a “pull-up” to 12 volts (power supply to the ECU) and a signal range from 0 to 12 V (theoretically, in reality the levels are slightly different).

GM systems use a different diagnostic protocol - ALDL. The ALDL adapter uses an open collector output and 5 volt signal levels. The “tightener” in these systems is located inside the ECU. In the vast majority of cases, the original adapter is not used for these systems; K-Line is used for diagnostics, either by lowering the “pull-up” voltage to 5 volts, or by selecting a resistor for stable operation at both 5 and 12 volt levels.

As a rule, specialized microcircuits are used to match signals. The MC33199 microcircuit is used for matching with the K-line and “separation” and “mixing” of signals. MAX232 is a specialized chip for matching various devices with RS232 (COM port standard). MAX232 contains integrated voltage converters that allow you to obtain the +/-12 V necessary for port operation and brings incoming signals to the required level. More “advanced” specialized microcircuits - DS275 performs the same functions as MAX232, but has automatic adjustment of output signals according to the input level and, importantly, does not require bulky capacitor “piping”.

Exists countless options adapter circuits, from the simplest, on two transistors, to fully functional adapters on specialized microcircuits. Naturally, it is advisable to use a good adapter on specialized chips.

When diagnosing foreign cars of the 90s, there is often a need for an additional line L (K-L-Line adapter); later models, as a rule, use only K-Line. K‑L-Line adapter diagrams can be viewed.

One of the most thorough “handicraft artists” I know ch0 zen posted on his excellent website the most detailed, step-by-step description of making an adapter for the MC33199 using the “iron” technology. Highly recommend. You can download all the information in its entirety.

A simple circuit with 2 transistors

You can see one of the simplest, but at the same time perfectly working circuit with two transistors in the figure. The diode protecting the adapter circuit from polarity reversal must have a minimum voltage drop, for example, a Schottky diode. In some cases, it is useful to select the value of resistor R4 within the range of 510 Ohm - 1 KOhm, measuring the current between the K-Line and the common wire within the range of 15 -20 mA. The main problem with adapters of this type is that the transistor transmitting the signal from the K-line to the computer (Q1 in the diagram above) closes slowly, which necessitates the selection of resistors to prevent oversaturation of the transistor. Otherwise, the signal front is greatly delayed, which leads to a lack of communication.
Several of these adapters work successfully, diagnosing all systems - from Mikasa to Bosch MP7 and with all block loader programs January 5 .1 .X. Sometimes, during unstable operation with the ALDL protocol, in which five-volt signal levels, it is enough to remove the K‑Line power resistor (in this case R4). Transistors used in the circuit are any low-power silicon n-p-n structures, for example, KT3102. It is advisable to select transistors with the maximum current gain value.

How to check the adapter without connecting it to the car? Very simple. The fact is that since the line after the adapter is single-wire, you can send a signal to the port and read it immediately (echo mode). To do this, you need to connect the adapter to the computer and use the ancient computer diagnostic program - Check It 3.0. We turn on the COM diagnostic mode and observe the reception and transmission of symbols in the windows. If everything goes well, this indirectly indicates that the circuit is working; to be completely sure, you need to monitor the RxD, TxD and K‑Line signals with an oscilloscope. The signal range at the COM port connector should be from +12 V to 0 V (ideally, actually a little less. The standard requires a range from +12 to -12 V), and on the K-Line from +12 V to zero. The adapter is also checked by the ICD diagnostic program.

K‑LINE © VSM adapter

A more “correct” adapter circuit for those who have problems getting the scarce MC33199 D microcircuit was sent by VSM. Here, for coordination with the port, the same, fairly common microcircuit MAX232 (ICL232 CPE, HIN232) is used, and for coordination with the diagnostic line - microcircuit 74 ALS04 (74 LS04, K555 LN1, K1533 LN1).

The circuit has been in operation for one and a half years, tested on all types of controllers. A protective diode is desirable with a low voltage drop, the second is any pulse one, for example KD521, 522. VSM also shared his experience in adjusting the load resistor. In the diagram its nominal value is 2 Kohm, this is optimal for testing and programming “January” blocks; for Bosch its nominal value is about 1 Kohm, for GM – more than 2 Kohm. I would like to note on my own that I use a resistor value of 510 -560 Ohm, as in “large” circuits, this provides a line current of about 20 mA, which increases noise immunity. In GM, I repeat, the load resistor is installed in the block and the diagnostic line uses five-volt levels; an external load resistor is not used in ALDL adapters. The numbering of the input pins corresponds to the 9‑pin COM connector, and the numbering of the outputs corresponds to the 9‑pin connector of the KR‑2 adapter from NPP NTS. The J5-Sport (Sokolov-Sport) sports injection system works most stably with this adapter. The rest, even famous adapters, did not connect the first time, they broke the connection, etc.

CHECKING AND SETTING

1 . We are looking for some kind of meter, at least a simple electrical tester.
2. Makes sure that the circuit elements are installed correctly and that the necessary connections are present and that there are no unnecessary connections between them.
3. We supply +12 V, the adapter is not connected to the computer.
4 . We check the presence of +5 V at pin 16 of MAX232 and pin 14 of logic, if not, check the correct installation and operability of 142 EH5
5 . We check the operation of the MAX232 converters, i.e. presence of +10 V on pin 2 and -10 V on pin 6, if not, check the correct installation and serviceability of the capacitors.
6. We supply RS232 -10 V to the receiver input, i.e. connect pins 13 and 6 MAX232 and check the signal flow: (logical “1” at output 12 MAX232) -> (logical “1” at input 5 LN1) -> (logical “0” at output 6 LN1) -> (+12 B in k‑line) -> (logical “1” at input 1 LN1) -> (logical “0” at output 2 LN1) -> (logical “0” at input 3 LN1) -> (logical “1” at output 4 LN1) -> (logical “1” at input 11 MAX232) -> (low level RS232, i.e. less than -5 V at output 14 MAX232). If the signal does not pass through any element, we check the correct installation and functionality of this element. We remove the connection between pins 13 and 6 of the MAX232.
7. We apply +10 V to the input of the RS232 receiver, i.e. connect pins 13 and 2 MAX232 and check the signal flow: (logical “0” at output 12 MAX232) -> (logical “0” at input 5 LN1) -> (logical “1” at output 6 LN1) - (~0 V in k‑line) -> (logical “0” at input 1 LN1) -> (logical “1” at output 2 LN1) - (logical “1” at input 3 LN1) - (logical “0” at output 4 LN1 ) - (logical “0” at input 11 MAX232) -> (high level RS232, i.e. more than +5 V at output 14 MAX232). If the signal does not pass through any element, we check the correct installation and functionality of this element. We remove the connection between pins 13 and 2 of the MAX232.
8 . We connect the adapter to the RS-232 port of the computer, connect it to k-line and try to establish communication with the controller. In case of problems, in the absence of an oscilloscope, we check: correct use of the program; COM port parameters (can it operate at the selected baud rate); resistor value in the k‑line load; communication line quality, etc.

Printed circuit board for this adapter (sent by Leonid [email protected])

Adapter K‑LINE © SHURIKEN

The second version of the “correct” adapter circuit for those who have problems getting the scarce MC33199 D microcircuit was sent by SHURIKEN (CTTeam). The adapter according to this scheme has been in operation for more than a year and a half, has been tested on all injection systems and is characterized as “reinforced concrete”. For coordination with the COM port, the same, quite common and cheap (in different regions, the price ranges from 30 to 50 rubles) MAX232 chip (ICL232 CPE, HIN232) is used, and for coordination with the diagnostic line - LM339 chip. The circuit does not have any additional features; coil L1 serves to filter impulse noise.

You can see the description of the settings and oscillograms. Just as in the previous diagram, the numbering of the input pins corresponds to the 9‑pin COM connector, and the numbering of the outputs corresponds to the 9‑pin connector of the KR‑2 adapter from NPP NTS.

K‑LINE: A new look at familiar things.

Progress is moving forward by leaps and bounds and is even looking beyond the gates of car repair shops, where more and more often you can find laptops as a diagnostic computer. There are no words, the laptop is more mobile, functional and, to some extent, prestigious, adding “weight” to the car service. But... Lately, complaints have become more frequent either about the malfunction of K-Line adapters, or, even worse, the failure of laptop COM ports. The point, it seems to me, is that on some laptops the COM ports operate with signal levels of +/- 3 V, while most adapters designed for PCs and assembled on MAX232 chips produce full +/- 12 V. That is, To work with a laptop, it is advisable to have an adapter designed specifically for this. The easiest way is to replace the MAX232 familiar to us all with MAX3232, having reduced signal voltages. The asking price is 90 rubles, which is exactly the difference in the cost of these microcircuits in Volgograd.

Another, and, as it seems to me (IMHO), more progressive method was proposed by HASS_78 - use for matching with a laptop port DS275 chip. This microcircuit works with the signal levels that it receives, adapting to either the COM port of a PC or a laptop, representing the optimal solution for implementing K‑Line. Among other things, this method practically does not require “tying” the microcircuits.

So, the circuit is from Hass on DS275 and MC33199.

..and MS

In conclusion, I want to say that despite the fact that this K‑Line adapter is very negatively received by assemblers and sellers of “adapters” based on a simpler and cheaper element base, this is the best and most correct solution to date.

APPLICATION

Difficult process. Even now, many people prefer to trust it exclusively to specialized service stations with appropriate scanning equipment.

Autonomous scanners allow you to identify all faults in the electronic and mechanical systems of a car quickly and completely.

The problem is the cost of the service. It is high and not accessible to everyone. Not even all auto repair shops provided such a service. Repairs, therefore, were most often carried out the old fashioned way - by the “scientific poke” method.

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.

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

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".

Interface for K-line - ISO-9141. Interface for L-line - ALDL.

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

Cable

The main differences between the modifications:

• conductivity,
• reliability,
• price.

The easiest way to buy a diagnostic cable is in online stores. In ordinary stores that sell auto parts, accessories of this kind of car are rarely found.

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

Diagnostic parameters for VAZ injection engines

What to pay attention to:

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.

How to diagnose a car yourself?

Not that difficult. Especially having high-quality modern equipment.

But no technology replaces knowledge and experience. Relying entirely on yourself, do not forget about the professionals at specialized service stations. Sometimes check their data as well. If something doesn’t work out for you, use their skills.

Repairs are always an expense. The car must be on the move - that's the main thing!

Andrey Goncharov, Expert in the “Engine Repair” section

There are many K-LINE adapter diagrams on the Internet. Available on COM, available on USB. The simplest circuits are on COM, but nowadays this is not convenient due to the lack of this port on laptops. USB circuits are a little more complicated. Microchips are used there, but they still need to be found. In addition, you need to make a printed circuit board. Therefore, I decided to do it in a simpler and more accessible way for everyone, using a data cable from old phones. Many people have this lying around in their back drawers.
We will need:
USB data cable from old phones (I used from Samsung c100/c110)
Radioelements (see diagram)
Soldering iron (and everything that comes with it)
Computer and some software

K-LINE adapter diagram

We assemble the diagram as conveniently as possible. We make a printed circuit board, or use a breadboard, or just a surface-mounted one (I chose the latter). Transistors VT1 and VT2 can be found in an unnecessary computer power supply, or bought at a radio parts store, like everyone else. Diode VD1 - any rectifier with a low voltage drop. If you are sure that you will not mix up the plus and minus wires when you use them, you don’t have to install a diode. Capacitor C1 is also not particularly important, it protects against interference.
Once we have assembled the circuit, we move on to the data cable. First, install the PL2303 driver for it. Be sure to support non-standard speeds. (Download the driver) After installing the driver, connect the cord and make sure it works. It should appear in Device Manager.

We remember what COM it is installed under.
Next, download the B&B COM test program (Download) to check the port.

Program

Data cable

We disassemble the data cable connector on the phone side and unsolder it. Now we need to determine which wire is which. To do this, connect the data cable to the computer, launch the program, select the appropriate COM port in it, any speed. Usually the black wire is negative. It should “ring” to the USB connector housing. Next, use a voltmeter to find the wire on which +3.3 volts. Measuring this voltage, we try to write something in the program window. If the voltage changes, then it is the TxD pin. Now we try to connect this wire to the remaining two wires (no need for minus). When connected to the correct wire, the entered information will be duplicated in the lower program window... which means this is RxD. Wires found. Now we solder these wires to our circuit. Before turning on anything, make sure there are no shorts in the assembled circuit or breaks (a wire accidentally came off). Check compliance with the diagram.

We check the functionality of everything we have collected. Again, use the same program to connect to the port, but do not forget to supply 12V power. The information entered in the upper window should be duplicated in the lower one. If this happens, then the circuit is working. Can be connected to the ECU.

OBDII connector

Download the OpenDiagFree program for diagnostics. In the settings, select our port and switch to the “Method 2” connection. We use it)

If you want to indicate the operation of the diagnostic cable, just solder the LED with a resistor, according to one of the options listed below. In the first option, the LED will always light up while the adapter is connected to the diagnostic connector. It will blink while data is being transferred. In the second option, the LED will only blink when transmitting data, and is turned off the rest of the time.
We select resistor R8 at least 470 Ohms. It is advisable to have an even higher value so that there is no effect on the K-line signal.

LED connection options

Note:

If you still have problems with the port speed, then try adjusting the values ​​in the ExtBaudrate registry.

Every car owner at some point is faced with the problem of diagnosing his iron horse, which suddenly stops starting and working normally. To solve this problem, most people use the services of car services, where a specialist with a miracle device can easily decipher the fault code of your car and help make qualified repairs.

What should a car owner do if the “Check Engine” light has come on on the dashboard of his car, but who does not have the time or money to pay a car service center to diagnose his car every time? Of course there is a solution, this manufacturingk lineDIY adapter.

If you are the owner of a budget foreign car like Daewoo or Chevrolet, as well as any domestic car except the latest models of 13-14 years with a CAN bus, then to diagnose your car, a regular k line adapter for diagnostics, which you can assemble with your own hands, will be enough for you.

Currently, on the Internet you can find a huge number of k line adapter circuits for self-assembly, designed to work through a COM port. Since this connector is currently not available on modern computers, circuits for assembling k line adapters without virtual COM port converters will not be considered in this article. If your PC has a COM port, you can download diagramsk line adapter for COM port.

Let's take a look at the build process DIY k line adapter for PC with USBports.

This diagram was collected and modified by the user Samokat Veterana.

For assembly we need:

Capacitors:

1) 100nF - these are SMD 1206 non-electrolytes (3 of them)

2) 4.7uF. x 10V - tantalum chip capacitor, powered from USB (can be used at a higher voltage value, use at a lower voltage value is unacceptable)

3) 10uF. x 16V - tantalum chip capacitor, powered from +12V side (can be used at a higher voltage value, use at a lower voltage value is unacceptable)

Any electrolytes from 4.7 µF to 100 µF can be used. Their task in this circuit is to filter out interference. Please note that the voltage should be no less than 10V and 16V, respectively.

Resistors size 0805:

1) 27 Ohm (2 pcs)

2) 270 Ohm (2 pcs)

3) 510 Ohm (2 pieces)

Chips:

Adapter circuit

Both adapters are factory assembled and have a one-year warranty.