Abstract: The base of a security/prevention system is an electronic device which has the capability of joining the performance of two functions, i.e. prevention of road accidents and theft protection of vehicles, using the principle of joint use of frequencies, whereby interference with the device's operation is prevented. The invention allows, on the one hand, such application in road traffic prevention in which an electronic security device installed in a vehicle provides passive or active warning of participants in the traffic as to possible momentary dangers requiring quick reaction of the driver. On the other hand, the invention allows such application in road traffic safety in which an electronic security device protects vehicles against theft; the device comprises three base units, i.e.