Abstract: The invention proposes an arrangement of the type comprising a unit into which a badge is introduced manually into a housing in the unit, and which comprises a lever for immobilizing the badge in an active position in the unit and an electromagnet made to lock the immobilizing lever, wherein this arrangement comprises a member for manually unlocking the immobilizing lever which acts on the mobile core plunger of the electromagnet. It is applicable on board of a motor vehicle in which the anti-theft functions are partially or completely fulfilled by data processing, some of which data represents an authorized user of the vehicle.