I wish I had looked this up. Would have saved me so much time!

Thanks for sharing the info here.

 

The mute button works completely different and separately from the other buttons. I hooked mine up via a relay to mute the radio as there was a mute wire lead I could tap into. Granted this was also before the head units had inputs in the back to control the system remotely and I had to do it via the IR method and had the first ever working dash controls in the public market. It got better as years went on and others such as Metra finally caught up.