A device for keeping a computer of a motor vehicle in a standby mode and for switching over to an active mode, with at least one electrical switch connected so that a change of an initial state of the switch constitutes an event that triggers the switching of the computer, and an electrical circuit incorporating each electrical switch, and an electrical power supply designed to exhibit two states: a power supply conducting steady state of each electrical switch wherein no power is consumed, obtained in the absence of a signal on its control input or upon the reception of a control signal of logic level “0”, and a blocked state wherein power is consumed, obtained in the presence of a control signal of logic level “1” on its control input.