Arrangement for positioning and fastening an equipment element in a motor vehicle

The assembly has a positioning unit comprising six pairs of complimentary contact surfaces of reduced dimension on a headlight (1) and on a cavity of a face bar or bumper face bar (2). The contact surfaces form an isostatic system. A fixing screw (3) locks a wall of the headlight and a wall of the face bar/bumper face bar. The screw locks the walls in a direction parallel to an X axis. An independent claim is also included for a motor vehicle comprising a lighting or signaling device constituting a headlight.