What do the buttons on the KDC475 do?

The buttons on the KDC475 have multiple purposes.

KDC470 Diagram

The large, front buttons on either side are the SCAN buttons.
The smaller button on the same side as the USB port is the UP button; this activates RECONNECT feature.
The smaller button on the same side as the battery door is the DOWN button; this activates DISCONNECT and KEYBOARD TOGGLE features.