The invention relates to a corner region between the lateral and rear roof frame of a motor vehicle having a rear door, and to a method for producing it. A first light guide and a second light guide are provided, with the first light guide being firmly attached to a housing of the air vent and the second Sight guide being firmly attached to the adjustment insert. The photometer may measure the optical property of the background along the path between the start position and the end position. An annular groove on the inner surface of the cap sidewall corresponds with a groove formed on the peg to retain a locking ring within the pair of aligned grooves when the cap is positioned over the peg on the pin. The solution is to reduce fuel consumption of the vehicle, wherein the hydraulic pump is activated during different operating phases of the vehicle at different lower pressure values in the event of a hydraulic pressure drop in the hydraulic accumulator of the hydraulic pump. Then, equalizers emphasize the harmonic component therein according to the response characteristic of the blue light and the response characteristic of the phosphor light for reduction of the dullness of waveforms.