GMC 2004 Yukon XL Owner's Manual page 246

Radio Display
Message
XL (Explicit Language
Channels)
Updating
No Signal
Loading XM
CH Off Air
CH Unavail
No Info
No Info
3-88
XM™ Radio Messages
Condition
XL on the radio display,
after the channel name,
indicates content with
explicit language.
Updating encryption code
Loss of signal
Acquiring channel audio
(after 4 second delay)
Channel not in service
Channel no longer
available
Artist Name/Feature
not available
Song/Program Title
not available
Action Required
These channels, or any others, can be blocked at a
customer's request, by calling 1-800-852-XMXM (9696).
The encryption code in the receiver is being updated, and no
action is required. This process should take no longer than
30 seconds.
The system is functioning correctly, but the vehicle is in a
location that is blocking the XM signal. When you move into
an open area, the signal should return.
The audio system is acquiring and processing audio and text
data. No action is needed. This message should disappear
shortly.
This channel is not currently in service. Tune to another
channel.
This previously assigned channel is no longer assigned.
Tune to another station. If this station was one of the
presets, choose another station for that preset button.
No artist information is available at this time on this channel.
The system is working properly.
No song title information is available at this time on this
channel. The system is working properly.