Rain Sensor on S320

[rikana]

Hi,
Soo... am out on the road and it starts to rain....wipers didnt come on automatically. How can i tell if my car has that rain sensor.....is there something to be set?? Plus my left wiper makes a scraping sound almost like it would if there was no rain on the windscreen.....the blades are quite new. What could be the cause??
regards

 

[tromppost]

To get into rain sensor mode "if you have it" you need to twist the stork to position 1