The present invention relates to a device (DISP) for identifying a position (PosB) of a secondary electronic unit (BA) on a motor vehicle (V), comprising: —a central electronic unit (PE) suitable for managing the power supply to a plurality of secondary electronic units (BA) and having: —a switching device (DC) for switching the power supply to all the secondary electronic units (BA); —a main timer (CPTA) suitable for being triggered in a time-correlated manner with the activation of the power supply to said secondary electronic units (BA) by said switching device (DC); —and said plurality of secondary electronic units (BA); wherein each of said secondary electronic units (BA) comprises a secondary timer (CPTB) suitable for being triggered in a time-correlated manner with the power supply to said secondary electronic unit (BA); and is suitable for performing internally at least one measurement of a voltage (VH, VL) when it is powered, said at least one measurement of a voltage (VH, VL) representing the position (PosB) of said secondary electronic unit (BA) on the motor vehicle (V).