51 for connection to the multiplexed bus of the vehicle in such a way as to exchange commands and status information of the light unit addressed on the multiplexed bus with the on board computer of the vehicle not shown the electronics card 53 or 54 is fitted with a controller not shown which participates in this communication via a standard connector whatever the lighting functions or ancillary facilities activated in the light unit moreover the electronics card 53 or 54 is connected to the electrical supply network of the vehicle by a supply connector not shown by a second harness 52 the electronics cards are associated with the light units on the left card 53 and on the right card 54 in such a way as to produce a set 61 of lighting functions and ancillary facilities determined according to the level within the platform envisaged halogen type lamps and simple manual adjustment of the orientation of the light unit are provided in the equipment of a light unit at level a of the platform at level b of the platform the electronics card 55 associated with the left hand light unit and the electronics card 56 associated with the right hand light unit are each provided with the same integrated controller as.