A motor vehicle light controlling device includes an operating switch and electronics assigned to the operating switch for supplying current to a multiplicity of lamps of the operating light system. At least one controlled switching component provides a clock-controlled supply of current to the assigned lamp circuit. The device is divided into a light switch module and a rear lamp module. A clock control provided, distributed over both modules, in order to influence the lamp currents of the vehicle operating lights. That is, in order to lower the luminosity of certain lights when required, and to be able to increase the on-board system voltage temporarily without the luminosity or lamp power changing as a result. The latter is of interest, for example, for the brief driving of electrical heating elements or servomotors to achieve an advantageously high utilization of conductor material. Lamps for driving light can be dimmed when the vehicles stationary to a luminosity corresponding to the customary parking light. Or, in the event of failure of a lamp or of a circuit for driving light, the corresponding headlamp can be supplied with current clock-controlled for lower light power for an emergency driving light function.