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Imobilizer[850/'95] posted by Björn Lindström on
Friday, 29 May 1998, at 2:51 p.m.

What technique is being used for the imobilizer function? The earlier models, in the '95 cars, used a separate black plug to be put into a mating hole in the dashboard and in the latest models it is integrated into the ignition key. I'm intrigued by the technology being used. Is it inductive, magnetic, optical, infra-red, radio based? From what I understand, it is also programable.
How safe can I be with such a system? How "crackable is it? --
Björne 855T '95

Re: Imobilizer[850/'95] posted by abe crombie on
Saturday, 30 May 1998, at 8:19 p.m.

The immobilizer used currently in Volvos works by pulsing a winding around the ignition lock at the instant that you begin to insert key into ignition lock. The key head has a transmitter that is powered by the pulses and broadcasts at one of a large possible number of frequencies back to the winding which also acts as an antenna. The immobilizer control module will pulse a random pattern and the key will broadcast back at its frequency in that random pattern. This prevents recording the signal and playing it back. The Motronic ECM has to get an authorization from the immobilizer CM to allow the car to run once the key has been verified. Any new key must be loaded into the immobilizer CM to be recognized by the immobilizer system.


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