Initially I was looking for info about the speaker way in the back corner in my wagon. It has never put out much volume, even when the radio is turned up pretty loud. And, with the parcel shelf in place it might as well not even be there. I know it works because when the volume is up I can hear music play and feel the grill vibrate (slightly) when I put my hand on it. In digging around I found the info above about the audio system, which indicates there a couple of features I wanted to confirm or set. One of them is the "Speed-dependent volume", another is the "Loudness ON/OFF". I know these are both supposed to be "On" by default but I've discovered several other things which had been turned off at some point in the past, and looks like these are 'off', as well.
The instructions are pretty straight-forward - press and hold down the 'band' button and then turn on the radio. However, other than switching to another frequency band (from FM to AM in this case) and the sound source moving from speaker to speaker, nothing functions as described in the instructions.