Rain And Light Sensor RLSM (4/162) [2018-2022]: Description

The rain and light sensor RLSM detects water on the windshield via optic measurement. An infrared light beam of known intensity illuminates part of the windshield. The intensity of the reflected light beam is measured and compared to the transmitted intensity. When there is water on the surface of the windshield, the light beam is slightly deflected and loses some of its intensity. If the light beam is not reflected in its entirety, the sensor interprets this as there being water on the windshield, and the windshield wipers are activated.

The rain and light sensor RLSM transmits information to the Central Electronic Module (CEM) about the outside light conditions, the amount of rain on the windshield, and sudden splashes on the windshield. The information is used by the Central Electronic Module (CEM) to request an appropriate windshield wiper speed.