Tony, the wired part is from the original steering wheel to the old radio. But to make it compatable with aftermarket radios they decided to turn the signal into an IR signal from the wired part. There is an IR transmitter that sits somewhere in front of the radio. This way the same system could be used with any aftermarket radio by simply changing the IR codes.

I can see why people like to keep their steering wheel buttons when they upgrade. It really is convienient.

Alex Lear