The control unit comprises a printed circuit board on which is mounted a plurality of components such as MOSFET transistors, in particular components of the so-called SMD type; and a support of plastics material, including a frame which has two opposite perimetral edges and from which extends at least one external integral formation in the form of an electric connector element in which are provided electrically conductive connector terminals which have respective ends which extend partly into the frame in a direction essentially orthogonal to the general plane of the frame, towards the first perimetral edge of this latter. The frame further has a support structure which extends into the frame between the two said perimetral edges; first integral retainer formations operable to hold the printed circuit board to the frame on a first side with respect to the support structure close to the first perimetral edge of the frame; and second integral retainer formations which extend from the support structure and are directed away from the first perimetral edge, that is towards the second perimetral edge of the frame and which retains at least one independent electronic component provided with wire rheofores, such as a capacitor, on the other side of the support structure. The rheofores of this independent component and the ends of the terminals extend towards, through and beyond the said printed circuit board and are soldered to it on its face opposite the support structure.