A setting device for a vehicle having a mechanically adjustable part in which a sensor assigned to the mechanically adjustable part generates sensor signals corresponding to the positions of the part. An initial range of the sensor values is assigned to an inoperative position of the part and covers the varying initial positions of the part. An evaluation device stores a longer constant signal in the initial range as an intermediate value. A longer constant sensor signal is compared with the intermediate value after the initial range is exceeded and after the subsequent return into this range. If it is established that both values are approximately of the same magnitude, the evaluation device stores this value as an initial value. As a result, the inoperative position of the part is reliably verified without the use of additional auxiliary components or steps.