According to the invention, an apparatus for automatically detecting a motor vehicle's generator type is proposed, in which the characteristic voltage course is measured at a terminal (DF) of the generator (1) and compared with values stored in memory. Via an interface (3), a control unit (5) is connected to the controller (2) or generator (1) and evaluates the voltage change (&dgr;DF) upon a load change. To that end, the voltage at the terminal (DF) is measured and evaluated before the electrical load (8) is turned on, after it is turned, and after it is turned off. By means of this apparatus, advantageously not only the generator type (A, B) but also incorrect installations can be ascertained.