The parking assistance system provides the driver with information whilst reversing relating to distance when approaching obstacles which are behind the vehicle, which could be outside the driver''s field of view.The information that there is an obstacle and its distance is transmitted to the driver by means of acoustic signals whose frequency varies according to the distance of the vehicle from the obstacle.An electronic control unit activates and controls the operation of the four sensors located in the rear bumper, processing the signals received and activating the acoustic signal inside the luggage compartment on the left hand side.The system is activated when reverse gear is engaged: under these conditions the control unit energizes the transducers and sends them a request signal, receiving response signals.The ultrasound technology sensors act as intelligent transmitters/receivers through a triangulation technique: this allows improved detection in critical situations or in the presence of small obstacles. The impulses emitted are reflected by any obstacles; the transducers therefore receives an echo which is converted into a digital signal and sent to the electronic control unit.The distance of the obstacle is signalled by sounds with intermittent impulses: the frequency of this signal increases gradually as the bumper approaches an obstacle: when the distance calculated is less than about 30 cm, the sound becomes high pitched and constant; the acoustic signal, on the other hand, ceases when the distance of the obstacle increases.For more details and information on the operation of the system, Characteristic of working principle 5580H PARKING OBSTACLE DETECTION DEVICEThe control unit has an autodiagnostic function: when it is switched on the control unit carries out an initial test on the sensors.which are then continuously diagnosed during the operation of the system.A fault with only one sensor inhibits the operation of the entire system: in this case, the system excludes itself: the failure status is signalled sending a suitable high frequency acoustic warning.The system is activated with reverse gear engaged; the signal that the reversing light See E2022 REVERSING LIGHTShas come on supplies the parking sensors control unit directly.