a circuit arrangement is disclosed for controlling an illuminating device , particularly light - emitting diodes , in a control device of a motor vehicle , comprised of at least one illuminating device , which is integrated in a switching circuit having a semiconductor component , and of a microprocessor , in particular having an integrated non - volatile memory , for generating a pulse - width modulated signal , whereby the pulse - width modulated signal is coupled to a control electrode of the semiconductor component , whereby the microprocessor generates at least two pulse - width modulated signals , the pulse - width modulated signals are coupled to the semiconductor component via a logical system and the logical system can be subjected to the action of an additional control signal via the microcomputer .