GMC 2003 Sierra 1500 Pickup Owner's Manual page 245

XMTM Radio Messages
Radio Display
Message
Condition Action Required
XL (Explicit Language
XL on the radio display, These channels, or any others, can be blocked at a
Channels)
after the channel name, customer's request, by calling 1-800-852-XMXM (9696).
indicates content with
explicit language.
encryption code no action is required. This process should take no longer
Updating Updating The encryption code in your receiver is being updated, and
than 30 seconds.
location that is blocking the XM signal. When you move
into an open area, the signal should return.
No
Signal Loss of signal Your system is functioning correctly, but you are in a
Loading XM Acquiring channel audio Your radio system is acquiring and processing audio and
(after 4 second delay) text data. No action is needed. This message should
1
CH Off Air Channel not in service
3-90