GMC Yukon Denalid Owner's Manual page 312

If the CD is not playing correctly, for any other
reason, try a known good CD.
If any error occurs repeatedly or if an error cannot
be corrected, contact your dealer. If the radio
displays an error message, write it down
and provide it to your dealer when reporting the
problem.
Using the DVD Player
The DVD player is controlled by the buttons on
the remote control, or by the RSA system,
or by the buttons on the radio faceplate. See
"Remote Control", under Rear Seat Entertainment
System on page 321 and Rear Seat Audio
(RSA) on page 333 for more information.
The DVD player is only compatible with DVDs of
the appropriate region code that is printed on
the jacket of most DVDs.
The DVD slot of the radio is compatible with
most audio CDs, CD-R, CD-RW, DVD-Video,
DVD-Audio, DVD-R/RW, DVD+R/RW media along
with MP3 and WMA formats.
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If an error message appears on the video screen
or the radio, see "DVD Display Error Messages"
under, Rear Seat Entertainment System on
page 321 and "DVD Radio Error Messages" in this
section for more information.
Playing a DVD
DVD/CD AUX (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.