GMC Yukon Denalid Owner's Manual page 318

To listen to a device through the rear auxiliary
input over the speakers, cycle the DVD/CD Aux
button on the radio faceplate until "Rear Aux Input"
is displayed on the radio. The RSA or DVD
Screen must be on in order for the radio to source
to rear auxiliary.
(Power/Volume): Turn this knob clockwise or
O
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.
318
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.