Take a look in the middle top of the windscreen, you`ll see a module there stuck/integrated to the inside of the screen, sort of purple ish in colour. That is the rain and headlight sensor I think.

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X5 3.0D 2003
Mods:
Webasto telestart remote kit
Aluminium running boards
Tv in motion & Aux input lead, Ice>ink to Ipod 3g.
DVD rear headrest screens and dvd sytem integrated in to main tv system via aux lead (watch tv or dvd in front and back)
Homelink Gate Opener, Chrome Grille Kit, chrome tailgate handle, Chrome Guage Rings, Tunit V-CR 086
Standard:
Bluetooth, comms pack, sat nav, sports pack, sports seats, dimming mirror, electric folding mirrors, memory seats, heated seats.