An illumination unit comprising a luminescence diode chip mounted on a chip carrier and comprising an optical waveguide is specified. Each module is provided with a diode, poled to prevent forward current from flowing in the return current path, for aiding in equalizing module currents. A fleet vehicle company associated with the vehicle is electronically identified based on the one or more vehicle identifiers. In both techniques, the overdrive pacing rate is decreased if no increase has occurred in the last Z cardiac cycles.