SI82.30-P-0006C | Service Information: Notes on operation of the rain/light sensor (RLS) | 23.8.04 |
MODEL 203 as of 1.6.03 with CODE (345) Rain sensor
MODELS 209, 211, 215, 220, 230 with CODE (345) Rain sensor
The customer notices that under a clear, cloudless sky (even without any direct rays of sunlight) the driving lamps switch off too late when the exterior lamp switch is in "Auto" position (automatic).
When there are no clouds in the sky ("blue-sky effect"), the physical principles governing the function of the RLS cause it to interpret the ambient brightness as conditions that are too dark.
This is caused by the fact that the sensor measures light in the infrared spectrum and that this range of the spectrum tends to occurs to a below-average degree when the sky is cloudless and clear.