Lamp unit for a motor vehicle of the type including at least one housing into which is inserted a lighting module which is fixed in the housing by means of at least one pivot element incorporating a rod of substantially horizontal axial orientation, carried by the housing, of which a spherical head is housed in a capsule integral with the lighting module, wherein it includes at least one retaining enclosure which is traversed by at least part of the rod, which is carried by a wall of the housing, and in which a seating receives the capsule supported vertically substantially aligned with the spherical head, so that the weight of the lighting module bears on the housing, and in that a sidewall of the enclosure has two flanges which are received in a slideway carried by the associated wall of the housing.