2012 Lexus HS 250h Owners Manual - Page 656

LKA (Lane-Keeping Assist) (If Equipped) While driving on a freeway or motor highway that has lane markers, this system recognizes the lanes using a camera as a sensor to assist the driver with staying in the lane. The LKA system has two functions. Lane departure warning function If the system judges that the vehicle may deviate from its lane, it alerts the driver using rapid beeping, indications on the multi-information display, and a sensory warning* given via the steering wheel. *: A slight steering torque is applied for a short period of time in the direction of the center of the lane. Lane keeping assist function This function will be active when the vehicle-to-vehicle distance control mode of the cruise control is set with vehicle speed above approx. 45 mph (approx. 72 km/h) and while the lane departure warning function is active. When the lane keeping assist function is active, a slight steering torque will be applied, to help the driver maintain the vehicle inside the lane.