Method and device to control power consumption in a windshield wiper unit

This invention concerns a method to detect the wetness state of a vehicle windshield surface ( S ) comprising a windshield wiper unit (1), the windshield wiper unit (1) comprising : - wiper blades (5) configured to wipe the windshield surface ( S ) when set in motion, - at least one motor (7) configured to set the wiper blades (5) in motion, - a controller (9), configured to control the at least one motor (7), the method comprising the steps : - measuring the power consumption of the at least one motor (7), - determining the wiping speed ( W ) of the wiper blades (5), - using the measured power consumption and determined wiping speed ( W ) to deduce a friction related coefficient of the windshield surface ( S ), - comparing the deduced value to at least one predetermined value in order to determine the wetness state of the vehicle windshield surface ( S ).