The invention concerns a device (2) for signalling in or lighting up a motor vehicle passenger compartment, which comprises a light source (6) and a light guide (4), the source extending opposite a main face of the guide (8), the guide comprising at least one coupling face (10) capable of reflecting at least a portion of the light emitted by the source into the guide, and at least two decoupling faces (12) set apart from each other and arranged in such a way as to reflect the light coming from the coupling face to an outlet face (14) of the guide. This device further comprises a reading light.
