What is an immobilizer in the car and what is it for

Immobilizer: what is this device?

As long as the novice driver has not purchased a garage for the car, he can keep the car in the yard, behind the house, in the yard of the neighboring house. How to secure your car from thieves? For this purpose, a special device was created, which provides protection of the car from theft – immobilizer. What is it in the car? It is an anti-theft device that will leave the thief “with a nose”. It was created later than the usual alarm system, but its functionality allows you to cope with the problem much faster and more effectively. Car owners who have purchased an immobilizer and use it are well protected from theft.

What is an immobilizer and what is it for

The immobilizer is an electronic mechanism that blocks the operation of some systems of the car. As a rule, this blocks the fuel or ignition systems.

The immobilizer prevents the intruder from starting the car. The hijacker will encounter a car that will not respond to his manipulations. The device may be included in the car. It is installed very covertly, and it is impossible to detect it by eye. The device blocks some modules of the car, preventing others from driving it.

The thief may be waiting for another variant of events. Some varieties of the device do not have an immediate stopping effect on the systems. It manifests a little later, when the car stalls on the road.

General view of the immobilizer

Video: what is the immobilizer

How the device works, and where it is located

The device is located inside the car. Every day, when the car owner inserts the ignition key, the immobilizer protection is deactivated thanks to elusive pulses. When the ignition key is removed, the protection is fully restored. There is a chip in the key that helps the device recognize the owner.

The device is a set of electronic elements. This electronic complex immobilizes the car when the protection is activated. To restore the work of the engine, you need to possess an ignition key with the appropriate chip.

The principle of operation of the device is to break the electrical circuit. Immobilizers are equipped with an automatic activation system. If the car is not used for some time, the protection is automatically activated. If an attempt to steal the car is detected, the systems of the car are subjected to blocking.

The device consists of:

  • control unit (sends commands, processes sensor signals, makes decisions);
  • micromobilizer (electromagnetic relay;)
  • ignition key (password, fixed in the chip, which is recognized by the protection).

The location of the device is carefully hidden. It is an encrypted system, whose operation is built through the regular power grid on high frequency waves. Often the components of the device are disguised as ordinary car equipment. The area of action is not great: it is a few meters.

The micro-immobilizer can also be disguised under the parts or appliances of the car. Sometimes it looks like an ordinary fuse, located in the block. To find and disarm the ten relays and sensors of this micro device, you will have to spend several days.

There are devices that start the engine interlock with a delay. Here the interlock circuits are not interrupted. They open when the engine is running. In this case the car stops after a few hundred meters of driving.

Working principle of the immobilizer

The most modern is the transponder protection system. It works on the contactless principle. The owner carries a card or a key fob with a cipher of greater complexity. In the cabin of the car is authorized, the system recognizes the owner, the protection is turned off.

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The receiver is almost impossible to find. To do this, you would have to look through the whole car. He can be located anywhere: behind the upholstery, in the panel of any mechanism, behind the seats.

Types of immobilizers

Devices can vary, as there are several varieties of immobilizers. They all have similarities and differences depending on the type to which they belong. The devices are divided into:

  1. Contact.
  2. Contactless.
  3. Mobile systems.

Products differ in different functionality, the degree of reliability. From this comes the cost of the device.

Contact .

This type of device is activated with a key. The key is inserted directly into the well, or brought to it. Activation, deactivation, control is performed with a unique, secret code, by pressing the keys. The disadvantage of the device is that the thief knows where the security device is located. This type of protection is gradually beginning to wear itself out.


The protection system is contacted by means of a card tag, a transponder. The receiving antenna is masked under the upholstery. Manage the system with a key fob, card-tag. The range varies from large to small.

With a small radius, usually equal to 10 cm, the subject of the cipher brought close to the antenna. The disadvantage of being close is that the intruder can track the location of the antenna.

Mobile systems

There are sophisticated immobilizers that respond to fingerprints, retina. Mobile protection is a delayed “immobilization” of the car. When you turn on the motor, the car begins to move unobstructed. After some time, the engine stops and the car stops. The protection is activated, it is impossible to continue driving.

In this case the blocking circuits are not broken. The operation of the engine provokes their opening. The immobilizer of this type is equipped with three relays.

Immobilizer connection diagram

Wiring diagram of the immobilizer

How to disable the immobilizer

Usually the disabling of the device is engaged by a specialist, but with some knowledge and skills you can cope and on your own. To do this, you need to have:

  • computer;
  • screwdriver;
  • PACK-loader;
  • wrench for 10;
  • insulation tape.

If the device is located above the electronic control unit, it will not be difficult to disconnect it. It is required to unscrew 4 bolts, nut. Then the controller is removed and disassembled. The device is disconnected, the information is erased, using a computer. PAC loader is attached to the controller. To restore the diagnostic line, jumpers are installed to provide communication with the ECU, diagnostic socket. Sometimes Flash is overwritten.

To preserve the other functions of the device, the incoming wires are cut. Then they are reconnected to each other. After the diagnostic line is restored, the connector is placed in its former place.

How to bypass the immobilizer

A malfunction in the ignition system can be a consequence of the safety device. This happens very rarely, but the way out is to bypass the device. It should be remembered that in this case the protection of the car is lowered. There are several legal methods of circumvention. Illegal methods will not be considered for logical reasons.

Method 1

The most simple and inexpensive way is to use an additional key. It is hidden under the panel trim and kept within the device’s operating range. The key is attached in such a way that the system is in the unlocked state. The protection for the car becomes weaker.

Method 2

One of the best options would be to buy a car with a built-in bypass unit. The auto start system receives a signal from the key fob and starts the car. With this method, the security of the car is kept at a high level.

Method 3

The immobilizer is excluded from the ignition system. In order not to break the machine, it is necessary to know how to install electrical equipment. Particular attention is paid to safety. The functionality of protection in this method is reduced.

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Method 4

You buy an additional bypass unit. The remote control of such a unit allows you to disable the device. Then the car is started. This is also one of the most acceptable methods.

It is advisable to install the device, if it is not built into the car, at specialized services. According to the reviews of car owners, most of them are satisfied that they have purchased and activated the immobilizer.

The device is the most modern anti-theft device. Specialists give preference to the immobilizer, believing that the future belongs to it. If the car alarms only scare the thief, signaling the owner of the trouble, the immobilizer protects the car by actively counteracting the thief.

Conventional alarm systems are outdated these days. Most manufacturers have turned to the creation of immobilizers, constantly modifying and improving them. It is a reliable assistant and protector for every car owner.

Why turn off the immobilizer: reasons and sequence

Why to disconnect the immobilizer: reasons and sequence

Modern cars are equipped with electronic protection systems. However, these nodes often conflict with the main electronics of the car in the process of performing their functions. The immobilizer (IMMO) is used as a protection system, which prevents the engine from starting without an access code stored in the chip on the key. The immobilizer is built into the vehicle’s electronic control unit (ECU). However, in some life situations, it is better to disable this security feature. This is the question – why disable the immobilizer and how to do it – our article will be devoted to.

How the immobilizer works

The word “immobilizer” has English roots. Literally it means “immobilizer”. In practice, it is a whole electronic system that performs the function of prohibiting the start of the engine if there is no chip with a unique code. To achieve its purpose, the immobilizer interferes with the operation of critical automotive components. Most often, the fuel supply and ignition systems are involved in the protection. The immobilizer blocks one or both of them at once.

Let’s take a closer look at how the immobilizer works. The algorithms of its operation can be divided into two types. The first simply disconnects the power supply to important engine components. The second supplies voltage to a specialized device, which directly blocks the work of the motor. Regardless of the principle of operation, the result is the same – the power unit of the car does not function. And simple ways of disabling the immobilizer will not work. If you break the wires or dismantle the safety device, the system will consider it as an attempt to break in and will block the car.

Immobilizers also have an auto-activation function. If the car is not used for some time, the electronics will automatically put the immobilizer into tamper-proof mode. The waiting time is usually determined by the manufacturer.

How the immobilizer works

The immobilizer usually consists of the following parts:

  1. The control unit. The electronic brain of the system. Receives signals from various sensors and issues commands to disable or activate the protection mechanism.
  2. Electromagnetic relay (micromobilizer). This is an executive mechanism, with the help of which the ignition control circuit breakage is usually realized.
  3. The car owner’s key. It contains a microchip with an embedded password. If the control unit recognizes the chip as correct, the car starts. If not, the car will be locked. The password is encoded in the chip in the form of a specific sequence of signals. In addition to the chip, a special card is used as security elements.
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There are two main types of car immobilizers:

  • Contact – activated by a key inserted into the ignition switch.
  • Contact – activated by a contactless device, which may be in the form of a card or transporter.

There are also immobilizers, which are activated and deactivated by entering a numeric code on a special keypad.

The way the immobilizer works resembles an alarm system. True, there are a number of very important differences. Modern alarm systems have the widest list of functions. For example, they send the owner satellite coordinates of the location of the car. Also, the owner will get a message in case of an attempted burglary of the car. The immobilizers have no such functions, performing only the role of blocking the motor and the movement of the car. That is why they do not need a large radius of action. Usually, it is measured in a few meters or even centimeters.

Immobilizers are often made in the form of miniature devices (relays). In addition, they are externally disguised as some other parts or devices. The most common variant is a relay, resembling a fuse. Installed in the block of these fuses, it does not attract attention. This means that an intruder will need an unacceptably long time to find and disconnect such a device. If there are several such microdevices in a car, it may take more than one day to find and disconnect them.

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There are immobilizers that produce a delayed motor lock. This is done in order to put the car thief in an extremely disadvantageous situation. That is, after opening the car is started as if nothing had happened. However, after driving a couple of hundred meters, the car turns off, because the immobilizer began to work. The intruder ends up in the immobilized car on the road among many cars and people. This attracts attention in itself. The thief has little choice: either flee as quickly as possible, or eliminate the reason for the stop, risking being caught.

Why to disable the immobilizer

Why disable the immobilizer

The main function of the immobilizer is to immobilize the vehicle. This is realized by disabling the engine after a specified distance or time. This function is very useful if the car is attempted to be stolen. But it can be quite inappropriate, if for some reasons it will work falsely, and the owner urgently needs the car.

In such a situation, the only effective remedy is to disable the immobilizer. This may be needed in the following situations:

  • The car battery is completely discharged and the code of the security device is knocked out.
  • The immobilizer system was connected incorrectly during the diagnostic process of the car.
  • Errors or complete failure of the electronic control unit.
  • Requires starting the vehicle’s engine remotely.

This list is far from complete. These are only the most common motives to get rid of the car protection.

It is possible to identify several groups of reasons for disabling the immobilizer:

  • Software errors.
  • Hardware malfunctions.
  • Interferes with the installation of other necessary equipment.

Each group of problems has a specific solution.

Hardware errors

The immobilizer will unlock the car if the codes recorded in the key and in the ECU memory are absolutely identical. An error occurs if there is a malfunction in the key or in the memory of the device. The system sees that the codes do not match and does not give commands to unlock the engine. The probability and frequency of these failures depend on the quality of the immobilizer manufacturing. If the quality is poor, errors will occur frequently. For example, VAZ cars are very prone to this problem. Failures in the program often occur due to the redistribution of charges in the ROM.

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These faults are inherent in the physical level of the equipment. The most typical ones are contact oxidation, burnout of relays and the like. Electronic devices are very much afraid of voltage drops, which are not uncommon in the onboard network of the car. It may happen that the electronic unit completely loses its functionality at the moment when the car is blocked. In this situation, the skills to disable the immobilizer are very useful.

Also common causes of immobilizer failure are break or shorted wiring, burnout of semiconductor elements and other parts.

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In winter, many motorists want to be able to warm up their car’s engine remotely. The immobilizer directly prevents this function, since in this case the engine must start without a security code. Therefore, the heating device is connected in such a way as to bypass the locking system. If the driver considers the presence of the immobilizer as a useless function, it is disabled altogether.

How to disable the immobilizer

Important note – it is better to disable the immobilizer if the driver is thoroughly familiar with his vehicle and the programming processes. An understanding of the electrical part of the car will also come in handy. In general, to describe the sequence of actions to disable the immobilizer is simple, since on any car this operation consists of similar actions.

The operation of both contact and contactless IMMO is based on the following principles:

  • reading the code contained in the chip by means of an antenna;
  • The electronic control unit compares the received code with the stored in the memory reference. If the signals match, a command is generated allowing the motor to operate. Otherwise the engine is blocked;
  • then the command is received by the microcircuit that controls the ECU;
  • it is the program of this chip that needs to be modified. More precisely, delete the data on the immobilizer. After that the latter can be simply disabled. In some cases, instead of programming, the chip is replaced with a new one.

Important: before disabling the immobilizer, you need to think once again whether there are no other ways to solve the problem. And only when all options for troubleshooting have failed, you can resort to disabling the anti-theft protection.

How to disable the immobilizer

To successfully disable the immobilizer, stock up on the following devices and tools:

  • screwdriver or Phillips head screwdriver;
  • 10 mm socket wrench;
  • Personal computer or laptop;
  • PAC-type programmer and its program, which must be downloaded from the Internet;
  • soldering iron and accessories;
  • duct tape.

Successful disconnection of IMMO is based on strict observance of the sequence of actions below:

  • find the electronic control unit and disconnect all connectors from it;
  • open the ECU case, find the necessary microcircuit on the board and dismantle it;
  • replace the microchip firmware using the programmer. New firmware should not contain information about IMMO;
  • carefully solder the chip back in place and reassemble the ECU;
  • now the ECU will not send any commands to the immobilizer, as it simply does not know about its presence;
  • in the IMMO itself you need to disconnect or cut the wires connected to pins 9 and 18;
  • connect the cut wires together and insulate the stranded place. This will allow the car diagnostic system to work correctly;
  • Install all removed equipment on regular places, connect all previously disconnected connectors to ECU.

Important: There is an alternative solution to disconnect the immobilizer, much less time consuming. You will need to use a device called “killer”. Its operating principle is similar to the universal key. Emulators are also widely used. Using such a device allows you not only to disable IMMO, but also to install on the car any alarm system from a third-party manufacturer.

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Domestic car industry is equipped with immobilizers with the same principle of operation, as the imported devices. VAZ cars (from “Kalina” to “Niva Chevrolet”) are notorious for frequent failures of electronic control unit. That is why disabling the immobilizer is very relevant for them. However, the protection devices installed in VAZ cars (imported Bosch M1.5.4, APS-6 and outdated APS-4, January 5.1. and VS.1) are of average quality.

In the process of reducing the cost of VAZ cars the quality and reliability of some units and assemblies has decreased. It also affected the immobilizer with ECU and their software. In some models, you need to dial the IMMO code by pressing the accelerator pedal, if the control unit is frozen.

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In general, the system, which consists of ECU, immobilizer and ignition key containing a chip, functions in the same way as on cars of other models and brands.

What car owners say about disabling the immobilizer

1. Driving interruption and disabling

“Before repairing an immobilizer or flashing a key, I always ask the client about the background of the issue. That is, I wonder what reasons or actions led to the failure of the IMMO.

After analyzing the information received, I found out that the most frequent problems were preceded by a strong discharge of the battery. Most often the charge drops below 9 volts. This phenomenon is very common in winter, but it also happens in summer. For example, the motorist went on vacation, leaving the car in the garage. Before leaving, he checked the battery charge, it was normal. Two weeks later he returned and found that the message “immobilizer activated” lights up when trying to start the engine, as well as a flashing indicator in the form of a car with a key.

Therefore, I recommend removing the battery terminal if the car is scheduled to be idle for a long period of time. In winter, this precaution will be very relevant. All immobilizer failures, without exception, have occurred when the battery discharge has been smooth.”

2. Immobilizer chip design.

“The key contains a chip that contains a special code. The immobilizer detects the chip and reads the code. Therefore if the immobilizer suddenly displays an error, two options are possible: the chip in the key is broken or the code stored in the memory is damaged or lost. When the chip is broken, you can use a spare key or go to the dealer for a new one if the car was purchased in the showroom. If there are problems with the ECU memory, you need to restore there the original code that coincides with the code of the chip”.

3. Unlocking immobilizer

“Disabling Lock mode:

  • Turn off the ignition.
  • Switch on ignition with the registered key.
  • Wait 5 seconds.
  • Switch off ignition
  • Repeat the steps 3 times.
  • The engine should start.

Lock mode is a lock mode. It is activated if there were several attempts to start the engine with the key without a chip”.

4. How to prevent the immobilizer unit from breaking

“Having once encountered an immobilizer failure, you don’t want to repeat this sad experience. Therefore, take certain precautions. The main one is to avoid discharging the battery. You should also avoid using cigarette lighter from other cars or power supplies, as the sensitive ECU doesn’t tolerate such procedures well.

5. is the immobilizer effective against theft

“It is not difficult for a good intruder to disable the IMMO. After all, somehow cars get stolen. There were cases when the car, in addition to the immobilizer, was equipped with additional protection devices, but it did not save from theft.”

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