ECU (ECU), VKontakte 2

ECU (ECU), VKontakte

ECU (ECU), VKontakte


ECU – electronic engine control unit (Eng. Engine Control Unit, ECU). This unit is a key element that is part of the engine management system..

The main tasks of the engine ECU are:

  • receiving information from numerous sensors (input sensors);
  • processing the data according to a given algorithm;
  • generating and sending control signals to actuators;

Actuators are structurally integral parts of various powertrain systems. Electronic control schemes provide the ability to flexibly and dynamically optimize both the most important basic and secondary parameters during engine operation. ECU control is applied to different engine operating modes.

The ECU electronic control unit constantly exchanges data streams not only with the engine and its sensors, but also with many other electronic systems. The ECU is a link in the chain of such controllers that control the braking system with ABS, automatic transmission, car security systems (AirBag cushions, airbags, etc.), immobilizer, air conditioning and other solutions. Data is transmitted via a special CAN bus (Controller Area Network).

The engine ECU controls the following critical aspects during the operation of the engine:

  • fuel injection;
  • the composition of the fuel-air mixture;
  • throttle operation (on XX and other modes);
  • turbocharging pressure;
  • valve timing system;
  • exhaust gas recirculation process;
  • operation of the engine cooling system;
  • ignition and its adjustment;
  • exhaust gas composition;

These systems together affect the power characteristic of the internal combustion engine, the torque indicator, the efficiency of the engine, as well as the toxicity of the exhaust, etc..

An ECU is a programmable electronic device that is a combination of hardware and software. The main element of the hardware of the control unit is the microprocessor, as well as a number of other components of the electronic circuit.

The engine sensors transmit analog signals to the computer, which are often signals that a voltage change has occurred. The received signals are converted by the control unit component into a digital format. The analog-to-digital converter is responsible for this..

The presence of such a component is due to the fact that the ECU microprocessor is capable of working only with a digital signal. The reverse circuit involves the reprocessing of the digital microprocessor signal into an analog one, since the ECU is required to send analog control actions to the actuators. In such cases, the conversion of the signal from digital to analog is carried out by a digital-to-analog converter.

As for the ECU microprograms, the control unit contains two basic computing modules. One of these modules is called functional, and the second control. The first module (functional) receives the signals received from the engine sensors. Further, the specified module performs signal processing and the formation of control pulses that are directed to the actuators of a particular engine system. The task of the second module (control) is to analyze the output signal, as well as its correction. Thanks to this ECU operation scheme, the engine can go into emergency mode, etc..

The ability to reprogram the electronic control unit is actively used for tuning a gasoline or diesel engine. A flashing of the computer may be necessary after certain changes that are made in relation to the standard design of the internal combustion engine (completion of the intake system and fuel injection, installation of a turbocharger or boost boost pressure, installation of tuning elements, refinement of the exhaust system, etc.). Additionally, the ability to flexibly adjust the firmware of the ECU control unit is used for software tuning of the motor, which was called chip tuning.

Each individual electronic vehicle system has its own control unit. All blocks are combined into a single connected circuit thanks to the CAN bus. Blocks connected by a bus are sometimes called a car computer, and the number of controllers can reach 80 or more.


CAN data bus 8

CAN data bus

Without keyword

Controller Area Network (CAN data bus)

Or colloquially: “CAN bus”.

In the period from 1984 to 1986, Robert Bosch GmbH invented, developed and put into production the CAN standard – Controller Area Network (network of controllers) , whose main goal is to unite in a single network various actuators, sensors, sensors, etc..

And as it turned out later, the CAN data bus really had many advantages over conventional wiring harnesses, some of which are:

Previously, this concept was thought little or not at all. Because the cars lacked a small bundle of wires and a couple of devices for the normal operation of the internal combustion engine.

However, technological progress goes forward, environmental issues, road safety and the driver, as a participant in this movement, come to first place, which leads to a constant increase in the number of electronic devices in the car.

What is “Electromagnetic Compatibility in a Car”?

This is the ability of the simultaneous and stable operation of many different electronic devices on a car without creating electromagnetic interference to each other. .

The CAN bus just meets these important requirements..

More specifically about this issue later.

Reduced cable connections

First, a little about what this bus is and what it looks like:

The CAN data bus is an ordinary “twisted pair”, as in the photo on the right. This is a specially twisted two-wire wire.

Various control units are connected to this twisted pair – they are called “users”. Data transmission is simultaneously on two wires of this “twisted pair”. It is important to know that the logical levels of the bus are mirrored: if a logical “zero” level is transmitted through one wire, then the logical “one” level is simultaneously transmitted through another wire.

Why is a two-wire data transmission scheme used:

  • for stability of error recognition
  • to increase and increase the reliability of data transmission

Assume that a voltage peak occurs on only one wire (for example, due to problems with electromagnetic compatibility) .

And then the receiver units can identify this as an error and ignore this voltage peak.

If a short circuit occurs or one of the two wires breaks, then thanks to the integrated hardware-software concept of reliability, it will switch to the single-wire mode of operation, and a damaged transmission line will not be used.

So, let’s continue about “reducing the number of connections between CAN bus devices”:

    Wires from the sensors are carried out only to the nearest control unit, which converts the measured values ​​into a data packet and transfers it to the CAN data bus.

Reducing the number of plug connections

Reducing the number of contact pins on the control units

  • Different systems can use signals from a single sensor (e.g. from a coolant temperature sensor)
  • CAN data packet

    Now let’s see what the “data packet” of the CAN bus is. It consists of seven consecutive fields (segments).

    The figure below shows eight fields, the last Intermission is Pause between data packets ”and it is not included in the Data Frame :

    CAN data bus 9

    The numbers in each field indicate the number of bits used in each message (data packet).

    Description of the data packet fields Start of frame

    Marks the beginning of the message (starts, bits) and synchronizes all bus modules.

    This field consists of an address identifier of 11 bits and 1 control bit and a request (Remote Transmission Request-Bit).

    This control bit marks the packet as a Data Frame (message frame) or as a Remote Frame (request frame) without data bytes.

    Control field

    The control field (6 bits) contains the IDE (Identifier Extension Bit) for recognizing the standard and extended formats, the backup bit for subsequent extensions, and – in the last 4 bits – the number of bytes of data stored in the Data Field (data field).

    Data Field

    A data field may contain from 0 to 8 bytes of data. A 0-byte CAN message is used to synchronize distributed processes.

    CRC Field (control field)

    The CRC field (Cyclic-Redundancy-Check Field) contains 16 bits and serves for the control recognition of errors during data transmission.

    ASK Field (acknowledgment)

    The ACK field (Acknowledgment Field) contains the acknowledgment signal of all receiver units that received a message on the CAN data bus without errors (acknowledgment – acknowledgment, sending a receipt – control message or signal issued in response to the received message) .

    End of Frame

    Marks the end of a data packet

    The interval between two data packets. The interval must be at least 3 bits. After that, any control unit can transmit the next data packet..

    IDLE (rest mode)

    If no control unit transmits messages, the CAN data bus remains idle until the next data packet is transmitted.

    Receive and transmit data

    The CAN data bus is a bi-directional bus – any of the connected units can either transmit or receive messages.

    In the above figure, the word Dashboard can be replaced with the usual (colloquial and more commonly used) “Gateway”.

    For example, on some cars, the dashboard (Audi, Volkswagen) is the gateway between the fast and slow buses, while the Mercedes has the EZS (ignition lock) as a gateway, although the panel itself works in two networks to display both salon and motor information.

    On the next generations of cars, since 2002, they began to use a separate ZGW unit (central interface), which acts as a gateway, stores auto equipment encodings, and through it diagnostics work on the CAN bus (namely, on the “clean” CAN – without k-lines).

    CAN data buses exist at different data rates and are sometimes referred to as “High-Speed-CAN” ) and “slow bus” (Low-Speed-CAN).

    For example, High-Speed-CAN is an engine bus, automatic transmission, etc., has a data transfer rate of 500 Kb

    Low-Speed-CAN is a bus for controlling windows, air conditioning, etc. , with a data transfer rate of 100 kbps.

    The order and format of sending and receiving messages by users is defined in the data exchange protocol.

    An essential distinguishing feature of the CAN data bus in comparison with other bus systems based on the principle of subscriber addressing is the addressing associated with the message.

      each message on the CAN data bus is assigned its permanent address (identifier), marking the contents of this message (for example: coolant temperature).

  • CAN data bus protocol allows transmission of up to 2048 different messages, and addresses from 2033 to 2048 are permanently fixed. The data volume of one message on the CAN data bus is 8 bytes.
  • The receiver unit processes only those messages (data packets) that are stored in its list of CAN messages received via the data bus (message destination control).

    Data packets can only be transmitted if the CAN data bus is free (that is, if after the last data packet was transmitted, an interval of 3 bits followed and none of the control units starts to transmit a message). The logical level of the data bus is recessive (logical “1”)

    CAN data bus: ADVANCED OPPORTUNITIES Diagnostics

    Since the signals from one sensor (for example, a temperature sensor, a speed sensor, etc.) can be used by different systems, in the event that the presence of a malfunction is displayed by all systems using this signal, the malfunction is usually a sensor or control unit, processing his signals.

    If the error message comes only from one system, although this signal is used by other systems, the cause of the failure, in most cases, is the control unit that processes this signal or the servo mechanism

    High level of data protection

    High level of protection of transmitted data is ensured even in case of strong interference.

    This ensures a high data transfer rate (up to 1 Mbit / s)

    Due to what this is achieved:

      Error Detection Mechanism Error Correction Mechanism

    Maintaining operability with a high level of electromagnetic interference

    Prioritization of teams

  • Real time operation
  • Interruptions in data transmission may cause errors. Such errors in data transmission must be recognized and eliminated. The CAN data bus protocol distinguishes between two levels of error recognition:

      mechanisms at the Data Frame level (message frame)

    On the basis of the message transmitted via the CAN data bus, the transmitter module calculates the control bits, which are transmitted together with the data packet in the “CRC Field” field. The receiver module recalculates these control bits based on the CAN message received on the data bus and compares them with the control bits received with this message..

    This mechanism checks the structure of the transmitted frame, i.e., bit fields with a given fixed format and frame length are rechecked.

    Errors recognized by the Frame Check function are designated as format errors.

    Bit Level Mechanisms

    Each module, when transmitting a message, monitors the logical level of the CAN data bus and, based on this, recognizes the differences between the transmitted and received bits. This ensures reliable recognition of global and local bits errors occurring in the transmitter unit.

    In each data packet, between the “Start of Frame” field and the end of the “CRC Field”, there must be no more than 5 consecutive bits with the same polarity. After each sequence of 5 identical bits, the block transmitter adds one bit of opposite polarity to the bit stream. Block receivers, in turn, delete these bits after receiving a message on the CAN data bus.

    Error correction mechanism

    If any CAN data bus module recognizes an error, it interrupts the current data transfer process by sending an error message. The error message consists of 6 dominant bits..

    Thanks to this error message, all control units connected to the CAN data bus are notified of a local error and, accordingly, ignore the transmitted message.

    After a short pause, all control units will again be able to send messages via the CAN data bus, with the message with the highest priority being sent first again (motor, automatic transmission, etc.).

    The control unit, whose message on the CAN data bus caused an error, also starts retransmitting its message (Automatic Repeat Request).


    If several control units simultaneously start transmitting messages, then it takes effect priority principle ”, according to which the message on the CAN data bus with the highest priority will be transmitted first without loss of time or bits (arbitration of access to the data bus) .

    Each control unit that loses the arbitration right automatically switches to reception and retries to send a message only after the CAN data bus is freed again.

    In addition to data packets, there is also a request packet for a specific message on the CAN data bus. In this case, the control unit, which can provide the requested data packet, responds to the issued request.

    In order to process data in real time, it must be possible to transfer them quickly. This implies not only the availability of a line with a high physical data transfer rate, but also requires the prompt provision of access to the CAN data bus if several control units need to simultaneously transmit messages.

    In order to distinguish between messages transmitted via the CAN data bus according to the degree of urgency, various priorities are provided for individual messages. The ignition timing, for example, has a very high priority, slip values ​​are average, and the outside temperature is the lowest priority. The priority with which the message is transmitted via the CAN data bus determines the identifier (address) of the corresponding message.

    An identifier corresponding to a lower binary number has a higher priority, and vice versa (the more zeros in the identifier (zero bits), the higher the priority) . The CAN data bus protocol is based on two logical states: the bits are either “recessive” (logical “1” – one) or “dominant” (logical “O” – zero).

    If the dominant bit is transmitted by at least one bus module, the recessive bits transmitted by other modules are overwritten.

    CAN data bus 10

    For example : When several control units start simultaneous data transfer, a data bus access conflict is resolved by “bitwise arbitration of requests for the shared resource” using the corresponding identifiers.

    When transmitting the “identifier field”, the transmitter after each bit checks whether it still has the right to transfer, or if another control unit is transmitting a higher priority message via the CAN data bus. If the recessive bit transmitted by the first transmitter unit is overwritten by the dominant bit of another transmitter unit, the first transmitter unit loses its transfer right (arbitration) and becomes the receiver unit.

    The first control unit (N 1) loses arbitration from the 3rd bit.

    The third control unit (N 3) loses arbitration from the 7th bit.

    The second control unit (N 2) retains the right of access to the CAN data bus and can transmit its message.

    Other control units can transmit their messages via the CAN data bus only after it is free..

    In this case, the right to transfer will again be granted in accordance with the priority of the message on the CAN data bus.

    That is, when using this principle of “priority”, there should be no conflict on the CAN data bus if several devices set different logical levels at the same time.

    Types of Existing Tires

    (for example, VW, Audi, Opel, Mercedes)

    Powertrain CAN (fast bus), which allows transmitting information at a speed of 500 kbit / s. It serves for communication between control units on the engine and transmission lines..

    Comfort CAN bus (slow bus), which allows transmitting information at a speed of 100 kbit / s. It serves for communication between control units included in the Comfort system..

    Types of tires according to Mercedes classification:

    CAN-C bus – “fast” powertrain bus.

    CAN-B bus – “slow”, salon “comfort” tire.

    CAN-D bus – diagnostic bus (used for diagnostics).

    In vehicles with CAN bus diagnostics, the ZGW unit (central interface) is installed as a gateway to all three buses. It’s been on more modern Mercedes since 2002.

    Color marking of tires on Mercedes

    “Fast” powertrain bus (500 kb / s) – green and green with a white stripe.

    The tire “comfort” – brown and brown with a black stripe.

    In the figures in various kinds of manuals and directories, CAN bus wires, for clarity, can be marked approximately like this:

    Common to all systems is the following:

    • Systems comply with the same data transmission requirements as specified in the relevant protocol..
    • Two signals twisted together (Twisted Pair) are used to transmit signals, which effectively resist external interference (for example, such a need exists when they are located in the engine compartment).

  • The same signal is transmitted by the transceiver of the control unit through both bus wires, but at different voltage levels; only in the differential amplifier of the receiving control unit is a single (differential and interference-free) signal generated at the CAN input of the receiving control unit ( The bus is differential and works only due to the voltage difference between the lines, and not between the line and the car body. Many “poke” regarding the “mass” and are surprised:
    I searched and found 12 volts on the slow bus relative to the body, where. After all, the specifications say 2.5 – 3.5 volts?).
  • CAN data bus applications

    (applied to Mercedes)

    Various CAN bus systems are used for the engine compartment and the passenger compartment, which differ in data transfer speed.

    The data rate on the CAN data compartment of the engine compartment (CAN-C) is 500 Kbps, and the passenger compartment CAN data bus (CAN-B) due to the smaller number of particularly urgent messages has a much lower data rate – 83 Kbps.

    Data exchange between both bus systems is carried out through the so-called “gateway gateways”, i.e. control units connected to both data buses.

    CAN-C (engine compartment CAN data bus)

    In the terminal control unit, a so-called data bus terminating resistor with a resistance of 120 Kom is installed on each side, connected between both wires of the data bus.

    Engine compartment CAN data bus activated only with ignition on.

    CAN-B (interior CAN data bus)

    Some control units connected to the interior CAN data bus are activated independently of the ignition (for example, central locking system).

    Therefore, the passenger data bus must be in functional readiness mode even with the ignition off (that is, the ability to transmit data packets must be provided with the ignition off).

    To reduce energy consumption as much as possible at rest, the CAN data bus goes into “passive standby” mode when there are no transmitted data packets and is activated again only with subsequent access to it.

    If in the “passive standby” mode of the CAN data bus of the passenger compartment any control unit (for example, the ceiling control unit (N70) transmits a message via the CAN data bus, only the master system module (for example, the EZS control unit (N73) will receive it)

    The corresponding master control unit stores this message in memory and sends an activation signal (“Wake-up”) to all control units connected to the CAN data bus of the passenger compartment.

    When activation is performed, the control unit (N73) checks the presence of all CAN data bus subscribers, after which it transmits a message previously stored in the memory.

    CAN bus topology

    CAN bus connection diagram called “topology”.

    Or: “A set of specific rules by which various devices are connected to the bus”.

    It depends on the model of a particular car and the manufacturer..

    For example, a star topology patented by Daimler-Benz. This topology reduces resonant problems in the line..

    CAN controllers are connected via a bus that has at least two CAN H and CAN L wires, through which signals are transmitted using specialized IC transceivers. In addition, IC transceivers implement additional service functions:

      Adjusting the slew rate of the input signal by changing the input current.

    The built-in current limiting circuit protects the transmitter outputs from damage due to possible short circuits of CAN_H and CAN_L lines with power circuits, as well as from a short-term voltage increase on these lines.

    Internal thermal protection.

  • Low power mode, in which the receivers continue to inform the controller of the bus status so that when information signals are detected on the bus, it can bring the transceivers to normal operation.
  • The most widespread are two types of transceivers (transceivers):

      “High Speed” Transceivers (ISO 11898-2),

  • “Fault Tolerant” Transceivers
  • Transceivers made to standard

    “High speed” (ISO11898-2), the most simple, cheap and provide the ability to transfer data at speeds up to 1 Mbps.

    “Fault-Tolerant” transceivers (not sensitive to damage on the bus) allow you to build a highly reliable low-power network with data transfer rates not higher than 125 kbit / s.

    Now that we’ve got a little familiarized with the concept of “CAN data bus,” we can briefly talk about how practical work was done to detect and troubleshoot CAN data bus on a Mercedes ML350 Reinstalled model.

    The error was this:

    CAN data bus 11

    This car came to Russia from America, was brought for sale, the defect was incomprehensible and “floating”: “the car can work normally for 15-20 minutes, and then the BAS ESP icon on the panel lights up and the entire data bus is turned off” .

    These practical classes were held according to the curriculum “Mercedes Master Class” at BrainStorm, the classes were conducted by Maxim Vasilievich Derenovsky (in the photo above, on the left: removes the motor block connector) .

    Up to this point, the car was already being tried to be repaired in another workshop. There they changed “according to indications” (?) The BAS ESP unit, which did not help to fix the malfunction.

    Then they were advised to “throw” two wires of the CAN bus bypassing the wing of the car.

    (This malfunction – rotting of wires on this wing and their failure, is a structural and technological flaw of the company).

    It didn’t help either. And then the car was delivered to these practical classes in order to find and fix the malfunction.

    Two recommended methods were used to troubleshoot:

      CAN bus resistance test

  • Turn off circuit blocks one at a time
  • Resistance test

    The bus is two twisted pair wires.

    Figuratively: “has a beginning and an end”, which are any two blocks. In these end blocks are matching resistances (“terminators” – dec.), 120 ohms.

      If the bus is working and the terminal blocks are connected, then on the bus we will see a resistance of 60 Ohms (two 120 in parallel).

    If there is an open on one of the end blocks, the bus will ring 120 Ohms, and more than 120 Ohms, if there are no end blocks at all.

    Units connected in parallel with a multimeter (by resistance) are not monitored.

    In ML350, one of the end blocks will be motorized, the second, depending on the year of manufacture, most likely AAM, EAM or EZS.

    Defining a short circuit in a CAN data bus is definitely a difficult task. What can I do:

      Visually inspect the wires to identify and identify external damage

    Disconnect the connectors of the control units and check whether the contact pins are bent in one or the second connector, whether foreign objects (dirt, pieces of wires, etc.) have got there.

  • Try to localize the troubleshooting and divide the CAN data bus into short sections, checking each of them sequentially
  • One of the students was asked to start the test by turning off the windows: “He’s hanging on CAN”.

    Wrong. The windows “hang” on the “slow” tire and even “if they really want to”, anyway “they will not put a” fast “tire”.

    We began to disconnect other blocks on the “fast” bus. There are a lot of them …

    On the EGS unit (box control) , located on the driver’s right feet, oil was found, as usual.

    It is oil that sometimes causes a malfunction of this unit.

    It’s hard to say where it comes from, but as an option, “according to the“ capillarity effect ”, oil from the box rises through the wires and seals through the seal leaks both onto the block and inside it, introducing an error”.

    This error is constructive: poor-quality seals of the wiring harness to the solenoids in the automatic transmission box. According to the harness, it rises to the electronic unit.

    AAM block – also turned out to be working.

    By the way, if you are talking about him:

      due to a “software failure”, he often “flies” the radio channel of the ignition keys. After “refilling” the block, the working capacity is restored.

  • Rolling keys can “fly off” (the car does not start, does not see the key)
  • The reason for the “gathering” of not only the radio channel, but also the rolling of the keys themselves, may be power problems. Scrolling the engine on a weak battery, smooth “landing” of the battery on the car, terminals, etc..

    But the bus itself will not cause such a rally. The maximum start enable signal from the AAM block will not reach the motor and even the starter will not be turned on.

    Disabling blocks also did nothing.

    We checked the numbers of the unit that was replaced – everything is fine, although there can also be confusion, since there are three options for specifications for ordering:

    – Mercedes company number

    This is a rather important point that should not be missed during Diagnostics..

    What is the “encoding” for the car:

    If it’s simple, then it’s “a single language in which control units can“ talk ”with each other.

    And since the car came from another workshop, and we don’t even know its history of “life and repair”, we had to check all the encodings.

    And they learned that in the dashboard it was written that “BAS is not integrated into the ESP” .

    They did the opposite – “BAS is integrated into ESP”, restarted the control system and error C1020 stopped appearing.

    What can be concluded : The reason for the malfunction of C1020 on this vehicle was incorrectly encoded vehicle equipment.

    However, do not assume that the “CAN error” is simple and can be quickly found and quickly eliminated..

    Just the opposite.

    As the experts say: “This is a pain in the neck and you can deal with it only with excellent knowledge of the“ psychology of Mercedes ”.

    This is on paper and in this article all the work to determine the malfunction was laid out in a few lines.

    Everything in life is much harder, harder and longer …

    BrainStorm Information Center


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    Chip tuning cars 2018

    Without keyword

    Chip tuning is “bad” and “good”, in other words, “correct”, and in my opinion, this particular tuning option is aerobatics in automotive diagnostics.
    About ten years ago, the words “He does chip tuning” spoke about the high professionalism of a person: if he knows how to “chip”, then this is almost the genius of automotive diagnostics.
    Now everyone is interested in chip tuning..

    And why not, if everything is surprisingly simple (in the past):
    Chip tuning – setting operating modes of electronic controllers by correcting internal control programs (firmware). Basically, the concept is used to indicate the correction of a program of a car engine control unit in order to increase power. In addition to the chip tuning, the use of additional electronic modules to solve similar problems is sometimes referred to. “This is from Wikipedia.
    And for this, now there is everything, offers the sea!

    Chip tuning cars 2018 18

    Now hundreds of car service workers are engaged in “chipping.” But in most cases it turns out either “zilch” or they “put the block” (what it is, you can read in the articles of the chip-tuner of the Moscow region Alexei Nitochkin on the Internet portal of the Legion-Avtodat company).

    And now I’ll tell you about such a “pseudo-tuning” car, get acquainted, the Hyundai Getz car.
    According to the external state of the motor, one can always assume its state:

    Chip tuning cars 2018 19

    When looking at this engine, it becomes clear that the engine has not seen even the simplest maintenance for a long time. The owner of the car is upset: “The car eats a lot of fuel.” He is asked an additional question: “- And are these all claims?” (you must always “pull” the client into a conversation, it happens that after such a detailed survey it is much easier to determine the malfunction).
    It turned out that the car was purchased not so long ago. Conducted a detailed diagnosis upon purchase? Yes, sort of like …

    I connect the scanner and watch the current settings. And the first thing that catches your eye is the illogical behavior of fuel corrections, “short and long” (LONG TERM FUEL TRIM, SHORT TERM FUEL TRIM – this can be found in the articles on the Legion-Avtodata Internet portal: “Fuel balancing – 2 parts”. The article was written more than 10 years ago and now something on the subject could have changed, but the basic understanding of the article can be taken out “.

    Or more clearly about Fuel Trim:

    Chip tuning cars 2018 20

    Figuratively: when you press the gas pedal, the driver only senses a speed increase, and inside the “electric car body” at this time there are many simultaneous (or almost simultaneous) actions, including changing the fuel adjustment parameters (adjusting the composition of the fuel-air mixture), short and long (Long Fuel Trim – LFT and Short Fuel Trim – SFT).

    It should be. And if this adjustment is not, then many questions arise.!
    It was not here, so what is the reason that on this car “long and short corrections constantly hung in the zeros”?!
    I press the gas, let go, keep it at higher speeds, sharply release the gas pedal – and the adjustments will not even budge.
    I conclude (according to these and other parameters) that the reason may be an unskilled interference with the firmware of the control unit.

    And so it turned out: someone did the “chip tuning”, turned off the main parameters, and now the control unit has nothing to “rely on”, it can neither enrich nor deplete the fuel-air mixture when changing operating modes. It is likely that the previous “chip tuning specialists” thus decided to reduce fuel consumption, but they thought in the wrong direction at all …

    In addition: “There was a constant error on the oxygen sensor“ Open circuit of the heater of the front lambda probe. ”And the reason for this in the photo:

    Chip tuning cars 2018 21

    If the photo is poorly visible, duplicate with the words: HOLE FOR OXYGEN SENSOR BREWED!
    And another point: the connector from the oxygen sensor “specialists from chip tuning” simply stopped hanging out in the air …

    Chip tuning cars 2018 22

    Needless to say, dirt, water, reagents from Moscow roads will get into such a connector very soon, and everything will begin to rot, rust, short-circuit and bring the car owner additional financial problems.

    What turns out: apparently, they wanted to sell the car so badly, moreover, with “minimal investment” that they did everything quickly and “tyap-lyap”.
    Now the car owner will have to shell out for a very expensive repair.

    To summarize: when buying this car, the client was either in a hurry, or his advisers were illiterate, but he did not do several important things:
    – I did not conduct an external inspection before buying, since it is simply impossible to not notice that the bore of the oxygen sensor is BREWED!
    – no fault codes were read, since a malfunction in the oxygen sensor heater would immediately show where to look

    Well, the last one, however, I don’t know if those “chip tuning specialists” who mutilated this quite good Hyundai Getz with their work will read this article:
    · It is impossible to carry out any work on the chip tuning of the car in the presence of any malfunctions (with the exception of some, as written in the articles of Alexei Nitochkin)

    This basic rule was violated, as a result of which the client did not buy a car, but a Problem, which he will have to deal with for a long time.


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    Diagnostic tools when working with cars 27

    Diagnostic tools when working with cars

    Without keyword

    Means – a method or tool to carry out any work or achieve any goal (source – Wikipedia)

    I decided to devote this article to various MEANS of car diagnostics, be it programs or devices that, to one degree or another, facilitate the work of auto-diagnostics. I will give real examples of the use of diagnostic tools on Lexus GS300 cars and other brands.

    Let’s start with the first: Lexus GS300 (2001), the motor is unstable. Simply put: “five points”. In such cases, an indispensable MEANS of assistance will be a motor tester. We connect to the desired points and remove the waveform. The oscillogram shows that the problem must be sought in the second cylinder.

    I forgot to say in order to know where to hook the measuring probes of the oscilloscope, i.e. more convenient places for connecting to sensors need information. And here comes the information tool, which is the program Motordata I open it and refresh the connection diagram in my memory:

    Diagnostic tools when working with cars 28

    Keeping in front of your eyes the scheme from Motordata or the necessary scheme in general – helps to concentrate and not to scatter thoughts around. And everything becomes somehow easier. Especially if the scheme, and just information in the native, familiar language.

    I just want to say that the device shown in the video is made “on my knee and with my own hands.” Similar, you can buy in the store, but why? If you have a head, there is a task and a goal, then it’s better to do it yourself and for your needs. And the money saved can be spent on something else no less necessary. For example, recently I bought myself “electronic eyes” J, a convenient thing!

    This is from the side, but it shows on the monitor screen like this:

    By the way, do you invest a lot in development? I don’t know who and how, but I always try to put the “extra” penny in equipment, because it will pay off for sure! As for the software … I will not advertise Americans and other giants such as AllData, everything is clear, whoever wants to will find where to buy / get this or a similar program. And since I am writing articles for the Legion-Avtodata company, I can say a few words about the Motordat program

    If these lines are read by conspiracy theorists and other dark people – do not read, this is not a balm for your soul, it is the other way around. I did not understand and cannot understand those people who are engaged in auto-diagnostics, but they try to save on software and do not even rock the boat to make auxiliary devices for their beloved ones – as in the video above, for example. And spend a couple of rubles on some kind of program – “better hang yourself.” However, to each his own. I am not saying that I am earning at the level of Comrade Abramovich, but I have enough. And Motordat’s program, for example, paid for itself in a few days..

    Sitting in the back seat and dreaming is easy. But “you can’t catch without labor …”. For example, a smoke generator “out of nothing”:

    Diagnostic tools when working with cars 29

    1 – compressor from an old aquarium
    2 – ordinary filter
    The green tube in the photo is “input”, blue is “output”.
    On the link below, a real example of using this tool.

    Since we have touched on the topic of diagnosing an idle system, the next home-made diagnostic tool is a four-channel LED indicator. With it, you can simultaneously observe the four signal sources, and see with your own eyes what’s there, the plus or minus potential, the “change”, or the complete absence of everything.

    Mitsubishi Lancer 9 (2006)

    “4 negative potentials are fed to the stepper motor (circuit above, circled) by the control unit in a certain sequence, the rod moves by the desired number of steps and thereby the required idle speed is reached.
    The LED lights up red or green, or does not light at all. The device can be called as a primitive “logical probe”.

    In this situation, I connect this probe to the control circuit of the four windings of the stepper motor and immediately see how the engine control unit works and whether there are open or short circuits in this circuit. It is checked simply, with the engine running, at different speeds, only two red and two green LEDs should alternately light up. The simultaneous illumination of three or four LEDs of the same color is a sign of a malfunction of the idle speed regulator, or its power circuits, or control. The brightness of the LEDs (two red or green) must be visually the same, otherwise there may be a malfunction.

    Consider the operation of this indicator probe at idle with periodic podgazovki.
    1. Alternating switching of two red and two green LEDs:
    Normal system operation
    2. Lights up red without switching to green:
    A control transistor or a given electrical circuit in an open circuit, or a short to (+).
    3. Green on without switching to red:
    Missing (+) power supply, winding in open or short circuit control circuit on (-).

    “Means for checking the regulator XX”

    Like any other device in the car, the XX regulator requires verification. This can be done in various ways, for example, as described in the article:
    “… We continue the verification. Check the presence of pulses on the idle speed controller (IAC)
    1. Impulses are.
    We can’t do without an oscilloscope. We look at the magnitude and duty cycle of these pulses. “.
    “System of stabilization of idling” > This is one option..
    There is another, simpler and more intuitive, see photo on the right:

    1 – LED control the operation of the device
    2 – on / off
    3 – reverse
    4 – plug block
    The principle of operation of this device is as simple as possible:
    – remove the standard connector from the regulator XX on the car
    – connect the device
    – select the direction of operation of the regulator XX (forward / backward)
    – visually observe the serviceability / malfunction of the regulator XX
    The general view of the device is shown in the photo on the right:
    1 – regulator XX
    2 – device
    3 – output to “negative” battery
    4 – conclusion to the “plus” battery
    – the fastest possible check of serviceability of the XX regulator directly on the car
    – quick, easy and inexpensive manufacturing of the device (time to manufacture is several hours, the cost of parts is several hundred rubles as of May 2009)
    – not found yet

    Something I digress from our sufferer Lexus. So, we settled on the fact that using various diagnostic tools we reached the engine control unit.
    Here, of course, I could figure it out myself, but I need to give way to the young? I had an assistant at that time, now he is in the army – a competent guy, there will be sense! In short, by opening the engine control unit and ringing all the circuits, we made sure that the reason is in the power transistor, we must find, buy and replace. Everything rested on time … I asked my assistant: “Will you take homework, otherwise I won’t get out of work soon?”.
    “Know the problems!” – He answered.
    In the morning, he went to the Chip & Dip store, bought the right transistor, arrived, soldered in – started the engine, it works stably, there is no “five-fold”. Done!

    Of course, when there are more worthy devices on sale that I cannot (I do not want) to make on my own, I just buy them:
    Search for wire breaks with the FF310 (1) AVTEL–wSVwkTtYI
    Search for wire breaks with the FF310 (2) AVTEL

    Another device made out “on the knee”.
    “Ignition System – Verification Option”

    When troubleshooting, when suspicion falls on the ignition system, it becomes necessary to check it. There are many ways to check, including the so-called “Scrolling by starter” – to visually determine “presence of spark”, etc..
    A simple example: a Mitsubishi car, according to the client, “when the gas was blown over, the engine periodically shook, unstable operation at XX”. Somewhere the customer was identified as malfunctioning: “The valves are to blame.” In our workshop, the opinion was different: “I need to see the ignition system”(with some work experience, some simple malfunctions can be caught by ear “).
    The peculiarity of this check is that the engine did not start at the same time. And for verification, a self-assembled “pulse generator” was used, the circuit of which is given below:

    Diagnostic tools when working with cars 30

    Another device made by yourself:
    “DTC P0304 *” Injector Test Option “MITSUBISHI GALANT”
    Not always the cause of the trouble code *P0304 * Cylinder 4 misfire detected * there are problems in the ignition system.
    Mitsubishi Galant, 2.4 liter, “American” entered the diagnostic procedure with a burning “CHECK” on the instrument panel and such customer complaints: “the car is shaking as if idling”.
    Verification showed:
    – ignition system OK
    – the vacuum test is normal
    – compression is normal
    But the “nozzle balance” showed the difference in nozzle performance …
    The most faithful would be to remove the nozzles, put on a stand and check each for their performance. But when there is no stand (under repair, as we had at this moment), or if it does not exist at all, then this question can be solved in another way. That is: “Check the injectors for performance without removing the injectors from the engine.” To control the nozzle, one of my self-made devices is connected. (they really make life easier and help with the diagnosis):

    Well and so on. If anyone is interested, then go to: D0% B5% D0% B2 & x = 0 & y = 0 & PAGEN_1 = 1 # content, there you type in the name “kudryavtsev” in the search and the search engine will give you all the articles with a detailed description of each self-made device and examples of their work when searching for a particular malfunction.

    The second Lexus, also the GS300, is only fresher.
    This is always the case: you look at the machine that came to repair, and it is so fresh, clean, you can’t even think that chaos of rust and desolation is happening inside …

    What is here?
    The ABS system light on the panel lights up, the stability control system and everything that is tied to the ABS system do not work. Another not unimportant diagnostic tool, which is difficult to do without, is a scanner. And the scanner showed an error in the front right wheel sensor circuit, or rather, an open circuit. He took off the wheel, examined the sensor externally, everything seems to be OK! Is there really a problem in the wiring or the ABS unit? It is necessary to emulate the presence of the sensor. I take another home-made diagnostic tool, the so-called dial-up resistor, of course you can take an ordinary constant, but with this it’s somehow more convenient and familiar.

    Connected, looked at the scanner for errors, everything is OK!
    So still the wheel rotation sensor is to blame!

    He took it off, put it on the table and began to inspect …
    And the client is behind:
    – The car is needed in how! – and edge of the palm of the throat, – do it, well, it’s very necessary …
    It’s ridiculous. Well, I’ll try, although the appearance of the car does not correspond to the content – dirt, rust, darkness, in a word. I begin to inspect closer:

    He just touched the postings – he broke off …

    So what to do? Of course, in another case … and what in another case? The client is familiar, with it we repaired a lot … we need help!
    He pulled the terminals out of the connector, contrived to replace the wires, insert them into the terminals, clamp, insulate, it seemed beautiful and reliable?

    Assembled, checked – it works. And you know how nice it is – it’s just humanly nice to see the client’s eyes and hear his simple:
    – thanks!

    Concluding this article, once again I want to pay attention to various diagnostic tools, whether they are purchased or self-made, everyone chooses for himself! Only one thing I want to say, without them the work of a diagnostician is long and painful;)


    • Diagnostic tools when working with cars 31

      Diagnostic equipment for cars – autoscanner, motor tester and oscilloscopes

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    Ignition system 36

    Ignition system

    Without keyword

    Ignition system 37

    The Toyota Chaser car (6 cylinders, 3 ignition coils, an external switch) arrived for repair with the following malfunction: “Starts up and stalls right away”.

    After the initial diagnostics, the suspicion fell on the IGF signal, which goes from the ignition coil to the engine control unit. External inspection showed that the wire is working (photo on the right).

    However, during the “bending and torsion” test, it turned out that the wire seems to be working only externally, and its inner veins are broken (photo on the right).

    After fixing this malfunction, the engine started working as expected..

    The car is repaired. Now you can summarize.

    The engine control unit uses the IGF signal to determine the performance of the ignition system..

    Based on the IGF signal, the ECM control unit performs an instant background calculation and further control of the injectors (nozzles) and the fuel pump (in systems where this is provided).

    If there is no IGF signal, the control unit stops the engine immediately after starting it..

    How the control unit monitors the IGF signal

    Two methods are used:

    1. based on EMF (electromotive force) in the primary coil. This method is not used in modern ignition systems due to possible inaccuracies and errors..
    2. based on measuring the current level in the primary ignition circuit. Minimum and maximum current levels are used to enable and disable the IGF signal. Current levels vary according to the state of the ignition system. If you use an exemplary oscillogram from the service manual, then we can draw a conclusion about the operation of the ignition system.

    No IGF Signal leads to a trouble code.

    Modern self-diagnosis systems, using the IGF signal, are able to specifically determine the idle ignition coil.

      – using one line and one IGF signal from each ignition coil
      – using a common IGF signal line from all ignition coils

    If the wire breaks from the ECU to the switch (IGT signal to the coil), the ECU monitors gaps in the IGF feedback signal and blocks the start by chopping off all nozzles (in subsequent systems, only the nozzle of a non-working cylinder is cut off) As a result, the engine runs for 3-5 seconds. and stalls

    The IGT signal is the switch control signal, IGF is the feedback signal, which is supplied from the switch to the computer. If this signal fails, the computer shuts off the fuel supply. According to various sources, if there is no signal on the IGF for more than 1 second on Х.Х., the fuel supply is turned off. According to other sources, if the IGF signal is absent for 8 to 11 pulses of the IGT signal, the fuel supply is turned off. On 3S-FE, code 14 is stored in the fault memory. This is done to eliminate the possibility of overheating of the catalyst from unburned fuel. The signals are rectangular in shape, amplitude 5 V.

    Ignition system 38

    Kudryavtsev Mikhail Evgenievich

    How to get there – picture on the right

    © 1999 – 2009 Legion Avtodata


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