It goes without saying, that a burglar-alarm system should prevent the possible theft of the vehicle itself or parts of it. Thereby, all the openings, perhaps even the filler-cap, can be monitored through contact-switches, possibly not the sun-roof or the side-windows, for the latter, the continuous testing of perhaps existing heating filaments is possible. For this reason, there may be a short wire embedded in the non-openable side windows.

The interior is additionally protected through infra-red- or probably nowadays, ultra-sonic sensors mostly installed in the left- and right B-pillars. The burglar alarm and the door-locking system work hand-in-hand with each other. The system is activated with either key or a remote control when all the doors are closed.

The optical alarm, where the hazard warning lights flash, may go on for 4 minutes in the USA, and for 5 minutes in all other countries, in Switzerland they may light-up continuously, otherwise they flash intermittently. Should an attempt be made to remove the radio, or to start the engine, the alarm may repeat itself. Therefore, the ignition switch and the electricity supply can also be included in the system.

In this case, with newer systems, a message can also be sent out and by broadcasting a permanent signal, the momentary position of the vehicle can be determined. Mostly, these systems, are still effective when the battery has been disconnected. Should the rightful owner move a certain distance away from the vehicle, the keyless systems can also be self-activating. Of course the burglar-alarm and the immobilizer work very closely together.

The monitoring is deactivated by unlocking the doors. There are vehicles which have a push-button for the one-time deactivation, e.g., to be able to leave a dog in the locked car. The ultra-sonic device may even register that the ventilation or the stationary heating has been switched on, in this case, the sensitivity of the alarm system is lowered. 01/12