I'm looking to interface my ipod with the steering wheel controls on my Miata (2007 w/ bose). I have a pinout of the connector, which lists 2 pins each for audio control switch and UART. Does anyone know what these two guys are? Is the audio control for the steering wheel and the UART for some type of serial control protocol?

Is the steering wheel control a resistor ladder or is it digital?

Thanks
CP