Fault detection of electric consumers in motor vehicles including at least one electric consumer switchably arranged between a first electric potential and a second electric potential. The electric consumer is switchably connected both to the first and to the second potential. A first switch is arranged between the first potential and the consumer and a second switch is arranged between the second potential and the consumer. The first and the second switch must be closed at the same time in order to operate the consumer. Fault detection is carried out when the device consuming the electricity is visibly off, in that a third electric potential is tapped at a voltage divider arranged parallel to the second switch. Fault detection is carried out by monitoring the third electric potential and the positions of the first and second switches.