Case closure detection system for a portable object

A portable object including a case middle closed by a back cover, in which an electronic module is placed, the electronic module including a plate to which a printed circuit board is secured, the printed circuit board carrying at least one contact area connected to at least one input of at least one integrated circuit, the integrated circuit supplying at least one signal to an electronic signal processing device. The portable object further includes a detection member changing from at least a first position, indicating that the back cover is secured to the case middle, to a second position, indicating that the back cover is not secured to the case middle.