I have just had a Sony head unit (model # MEX-BT3900U) installed in my Audi S4 Cabriolet (2006). The installer said that in order for the steering wheel controls to work, I need a Dietz CAN BUS adapter for Sony. The one he gave me as an example is a Tyco Alpine adapter (item # 3-957419-1), which has a 3.5mm male plug on one side, a 25cm cord and a small "box" connector that is approx. 3cm x 2.5cm. He took this Tyco adapter out of the car when he removed the Alpine head unit and installed the Sony unit. This Tyco adapter (which says "BMW" on it) did not work properly with the Alpine head unit. Can anyone assist me with the correct CAN BUS interface that matches Sony and works with my Audi steering wheel? A photo of my steering wheel is attached. Thanks from a newbie!