I am planning on a project in the distant future and need some questions answered.

I have a 2005 Scion xA. as you know 05 & 04 did not come with steering wheel controls but the 06 did. I have an after market Head unit that is compatible with steer wheel controls.

Does anyone know how the steering wheel buttons are powered up? Like would I need a new steering wheel and clock spring? from looking at images the 05 clock spring looks like the same one as the 06 clock spring. Furthermore I am actually more interested in the 2012 Lexus Ct200h steering wheel. I know most Toyotas have the same spline so I believe the steering wheel it self would fit. Also the two plugs the red and black one on the airbag looks like it will fit as well. Can anyone explain to me if the CT200H steering wheel will fit in the xA and whether or not the airbags will function and how to hook up wires to get the steering wheel buttons to work with the after market double din headunit, also will the horn work?

Thank you,

Wongjunkong