Thread: Remap stereo buttons on steering wheel for train horn?

I'm thinking about having a train horn installed for ****s and giggles but I don't want to have it hooked up to the main horn circuit. I never play CDs so I was curious how hard it would be to remap the CD Play button on the right side of the steering wheel to activate the train horn instead, while keeping the regular horn intact for keyfob use and regular road rage.

Does anyone know how the steering wheel stereo control buttons operate? Is there a single devoted wire to each button that connects out of the wheel through the DIN into the back of my stock stereo? Or is it more complicated than that?

'07 GP GT, stock XM stereo.

Steering wheel controls unfortunately use class 2 data. The only way I can think of achieving that short of decoding the transmission protocol and intercepting with a custom arduino or something is maybe by using the steering wheel control interface for aftermarket radios. I haven't used them, but there's definitely some decoding going on here. I think it would be a cool project though. If you do it, you'd be the first!