Lighting device for motor vehicle

The device (10) has a light emitting diode arrangement (12), a diffusing panel (14) or similar and a control and/or evaluation unit that controls the light emitting diodes so that in each phase at least one diode (12') operates as a light emitting diode and at least one as a photodiode and the output signal of the one acting as a photodiode is fed to the control and/or evaluation unit for evaluation. AN Independent claim is also included for the following: (a) a method of operating an inventive illumination device, especially for a motor vehicle.