Anti-Theft System Repair

During usage or a the moment of purchase a car on the secondary market, you might face with the need of repairing or reconfiguring alarms and other anti-theft systems. There can be a lot of different reasons: contacts become oxidized over time, settings are knocked down, some elements need to be replaced. If a security system installed on a car (as immobilizer, for example) fails, you can contact me, I will do a qualified diagnostic and repair.

Works of repair and adjustment of anti-theft systems

  • Diagnostic of the existing alarm system, especially after installation at an authorized dealer
  • Adjustment of the anti-theft system and alarm system for individual requirements
  • Strengthening the anti-theft properties of the existing protection
  • Implementation of autorun, if the car alarm potentially supports it
  • Writing additional key fobs and labels
  • Repair of alarm key fobs
  • Change and update the firmware of the software (SW)

A bit of theory - what are Immobilizers, anyways

The immobilizer was the factory (standard) electronic system - a part of the engine management system. It prevented the engine from starting when trying to use a self-made ignition key or trying to do without a key at all. The system cannot be neutralized by preliminary manipulations with the wiring (exceptions are single). Thanks to advertising, the term "immobilizer" entered our minds as "the most effective anti-theft tool", and only.

The standard car immobilizer works on the principle of limiting access to the ECU engine, implementing password access. Immobilizer should not be confused with other regular security equipment. It is an independent system that neither program nor hardware has an anti-theft attitude, and performs its role as a completely independent level of protection. Unfortunately, the word "immobilizer" is sometimes used in a wrong way with another meaning. So it can happen with a literal translation of survey materials about immobilization of vehicles. The phrase "... distinguish between mechanical (for example, the wheel lock), electromechanical (for example, benzenelectroclap) and electronic versions of immobilizers" contains an obvious mixture of meanings and implies the reader only a literal, vulgar understanding of the word "immobilizer". In fact, the immobilizer does not "immobilize" the car, but the engine control unit. Of course, physical locking devices should cease to be called immobilizers, if this stretch is not an advertising trick, then it creates confusion in any case.

So, an immobilizer is an access restriction system that can block the engine at the level of its ECU program. No software lock - no immobilizer.


New generations of immobilizers

These systems include the principles of active remote and transponder action devices. Combining the principles brings the flexibility of remote access aids to the immobilizer. It allows you to change the access password every time you turn on the ignition, and each new password is generated automatically instead of the previous one.

The main block of the security system operates with the same "reserve" of passwords and changes the currently valid password according to the same rule as the key fob. Once synchronized, the unit and key fob select the same password options. In each cycle, the block compares a pair of changing words. And also checks the used key fob on an accessory, comparing its ID with the list of numbers-identifiers registered in the memory corresponding to a complete set of fobs of the user. The described technology is often called dynamic coding, although this way of identifying "one's own" is not dynamic. And it does not apply to encryption as well.

In immobilizers with a rolling password, pseudo-random sequences are used with the difference between signaling and a key fob that transponders do not have their own word search generator. The transponder is of the Read / Write type, namely, allows you to change the contents of your memory repeatedly. In signaling with two-way communication, more complex cryptographic algorithms are implemented.

Such kind of ignition keys with a crypto-transponder are often called "crypto-keys". A crypto-transponder is called so because it has a built-in encryption function and this differs it from other types of transponders. Another name is a "transponder with a digital signature". The encryption keys are individual in this case. Therefore, now the "password rule" turns out to be unique for each transponder instance. The encryption keys do not appear, except for the one-time registration of the cryptokey, so it's almost impossible to intercept them. Compared to the algorithm of the rolling password, security increases, because interception at the stage of recording in the transponder becomes useless.

Note that both algorithms (rolling and crypto) are sometimes not distinguished and are called the "floating" code algorithm.

The next generation of transponders was called "transponders of cryptographic access" (CET). СET allows you to open the car and unlock the immobilizer with a single system, the manufacture of which is cheaper than two independent (security and immobilizer). While using a power source, the range of the new key is at least 30 m, and without a source - within 15 cm.

The next step in the direction of creating such devices is a keyless access technology, when the car opens when the owner approaches. When the owner sits on the seat, the transponder (for example, in the form of a card) is recognized, and the engine can be started by a simple press on a button.

The convenience of a regular immobilizer is that the car owner does not have to take any special action to turn it on or off. Everything happens by itself by inserting and removing the key and turning the ignition on and off. Couple times I had to talk with people who did not even suspect that their vehicle was equipped with a regular immobilizer.