Safety belt for a vehicle

The seatbelt has a mechanical detection unit (24) for detecting movement of the seatbelt strap (10) for activating an electroluminescent diode lighting unit in the seatbelt socket (20), behind a translucent cover (21), for illuminating the seatbelt buckle (18) and/or socket when the seatbelt is moved from its stored position. The lighting unit facilitates engagement of the seatbelt buckle and socket to assist with use of the seatbelt. The seatbelt strap has one end anchored on the structure of the body of a vehicle and another end connected to a roller (26), with the mechanical sensor changing state when the diameter of the roller passes a maximum diameter indicating that the seatbelt is not being worn. A control unit (28) deactivates the light when the seatbelt is properly fastened. An Independent claim is also included for a process for controlling a lighting unit in a seatbelt.