I stumbled upon this by accident and a check of the OM shows that it's described there:
I thought that the only way to seek radio stations up and down, or change tracks with steering wheel controls, was to have the center screen in 'Entertainment' mode and use the right toggle. I guess I never even noticed the the arrows there. However, the phone buttons (answer/hang up) buttons serve that function no matter what other mode is displayed in the center screen.
A Volume up.
B Volume down.
C Seek up or next.
D Seek down or previous.
Press the seek button to:
- Tune the radio to the next or previous stored preset.
- Play the next or the previous track.
Press and hold the seek button to:
- Tune the radio to the next station up or down the frequency band.
- Seek through a track.