Almost always, in the configuration of a purchased new car, the line “regular immobilizer” appears, and used cars for the most part are not deprived of such a device. Moreover, many owners do not even know that it is in their car, since its operation is not noticeable during everyday use, For this, in this article, we will explain in detail the following points related to this system.
- What is an immobilizer?
- The working principle of the immobilizer system
- What are the advantages and disadvantages of the immobilizer system?
- Can the immobilizer device be replaced by the alarm device?
What is an immobilizer?
An immobilizer is an electronic anti-theft device, the function of which is to prevent the engine from starting and driving in the event of an attempted theft. Actually, the main function of the immobilizer is hidden in its name - from English the word immobilizer is translated as "immobilizer".
Structurally,
immobilizers can be different - for example, some can open the car's electrical
circuits responsible for ignition or fuel supply, while others can work via the
CAN bus, programmatically blocking the engine start. However,
functionally, all immobilizers have a single purpose: to ensure the
impossibility of starting the engine and further independent movement of the
car in case of theft.
In everyday use, the
operation of the immobilizer is invisible to the car owner: as a rule, a key or
key fob is used to unlock it, which, getting into the ignition switch or simply
within the coil antenna of the immobilizer unit, turns off the immobilizer
system and allows you to start the engine without hindrance.
The working principle of the immobilizer system
The
operation of the immobilizer is organized as follows: when the ignition is
turned on, the immobilizer unit briefly sends a high-frequency signal to the
communication coil with the key chip and waits for the response code through
the same coil. Through this high-frequency signal, power is supplied and
communication with the chip in the key is carried out. In some systems,
the immo also transmits a unique request code that tells the key chip that the
reading is performed by a “native” car (almost all European and Japanese cars
since 2000). In response, the chip sends its personal code. The
received code is compared with the codes of the recorded keys in the
immobilizer's memory, and if it matches, then a connection is established
between the immobilizer and the engine control unit. Communication takes
place digitally or via a K-line or via a CAN bus and is a
request-response. The ECU sends 4 bytes of a random number to the immo,
the immo encrypts these bytes in a certain way and sends 4 bytes of response back
to the motor unit. If everything is correct, then the engine is allowed to
start. If at any stage a failure occurs, the engine starts and immediately
stalls. Both the operation of the fuel pump and the pulses to the
injectors and the supply of sparks to the candles are interrupted. The
prohibition of launch is at the program level.
What are the advantages and disadvantages of the immobilizer system?
The advantages of the immobilizer as an anti-theft device are obvious: it provides a certain level of protection against car theft, while often included in the list of standard equipment and does not require additional installation. The degree of protection depends on the type of immobilizer, as well as on the place of its installation: the easier it is to get to it by opening the car, the less potential protection against theft it provides. This, by the way, is the main disadvantage of standard immobilizers: they are convenient because the unlock chip is built into the standard key and does not require additional manipulations to start the engine, but the problem is that standard immobilizers are installed on the conveyor in a regular place, and the hijacker, knowing where the immobilizer is located in a particular model, can quickly “defuse” it.
Can the immobilizer device be replaced by the alarm device?
A specific answer cannot be given to it simply
because the alarm and immobilizer are devices that are different in
functionality. The alarm, as you know, serves to alert others and the car owner
when trying to steal, attracting attention with light and sound signals and
transmitting relevant information to the key fob. The immobilizer, on the other
hand, does not notify anyone of an attempted theft, but only prevents its
implementation, so the alarm and the immobilizer may not replace, but only
complement each other.
It should be noted at the same time that most
of the alarms have their own additional immobilizer, which is installed in pair
with the regular one or, in its absence, as the main one. The advantage of this
non-standard immobilizer is that, unlike the regular one, it can be placed in
an unknown and hard-to-reach place for a hijacker.