GMC 2004 Sierra - Manual (Page 247)

Radio Messages
CAL ERR (Calibration Error): Your audio system has
been calibrated for your vehicle from the factory. If CAL
ERR appears on the display, it means that your radio has
not been configured properly for the vehicle and must be
returned to the dealer for service.
LOCKED: This message is displayed when the
THEFTLOCK
® system has locked up. You must return
to the dealer for service.
XM™ Radio Messages
Radio Display
Message
Condition Action Required
XL (Explicit Language
Channels) XL on the radio display,
after the channel name,
indicates content with
explicit language. These channels, or any others, can be blocked at a
customer’s request, by calling 1-800-852-XMXM (9696).
Updating Updating encryption
code The encryption code in your receiver is being updated, and
no action is required. This process should take no longer
than 30 seconds.
No Signal Loss of signal Your system is functioning correctly, but you are in a
location that is blocking the XM signal. When you move
into an open area, the signal should return.
Loading XM Acquiring channel audio
(after 4 second delay) Your radio system is acquiring and processing audio and
text data. No action is needed. This message should
disappear shortly.
CH Off Air Channel not in service This channel is not currently in service. Tune to another
channel.
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