2007 GMC Yukon Owner's Manual - Page 318

O (Power/Volume): Turn this knob clockwise or counterclockwise to increase or decrease the volume of the portable player. You may need to do additional volume adjustments from the portable device if the volume does not go loud or soft enough. BAND: Press this button to listen to the radio when a portable audio device is playing. The portable audio device will continue playing, so you may want to stop it or power it off. DVD/CD AUX (CD/Auxiliary): Press this button to cycle through DVD, CD, or Auxiliary when listening to the radio. The DVD/CD text label and a message showing track or chapter number will appear on display when a disc is in either slot. Press this button again and the system will automatically search for an auxiliary input device, such as a portable audio player. If a portable audio player is not connected, "no aux input device" will be displayed. If a disc is in both the DVD slot and the CD slot the DVD/CD AUX button will cycle between the two sources and not indicate "no aux input device". If a front auxiliary device is connected, the DVD/CD AUX button will cycle through all available options, such as: DVD slot, CD slot, Front AUX, and Rear AUX (if available). See "Using the Auxiliary Input Jack(s)" later in this section, or Rear Seat Entertainment System on page 321, "Audio/Video (A/V) Jacks" for more information. 318