A vehicle door module includes a door trim defining a plane and a window regulator rail separably fixed to the door trim. The rail is fastened to a door at a fastening point. A projecting line extends from the fastening point and perpendicular to the rail to intersects the plane outside the door trim A method for assembling the door module in a door includes introducing the window regulator rail into the shell of the vehicle door, fastening the fastening point to the shell, and separating the door trim from the rail. Access is not impeded by the door trim. The arrangement simplifies mounting of the window regulator to the door.