The present invention relates to a motor vehicle's light module for lighting or signaling device purposes and includes at least one light source mounted on a support, an optical unit that engages the light source that forms a light beam and a locating system, which includes at least one locating pin inserted into a locating orifice. The support contains at least one locating pin and the locating orifice while the optical unit has the other locating pin and locating orifice. The locating pins include two facing parts where one of the parts is identified as the rigid part, and the other of the parts is identified as the flexible part, where the one part is more rigid than the other of the two facing parts.