GMC 2004 Sierra 1500 Pickup Owner's Manual page 258

If the current tuned station does not broadcast traffic
announcements, press this button and the radio will seek
to a station that does. When the radio finds a station that
broadcasts traffic announcements, it will stop and TRAF
will be displayed. When a traffic announcement comes on
the tuned radio station you will hear it. If no station is
found, NO TRAFFIC will appear on the display.
If TRAF is on the display you can press the TRAF button
to turn off the traffic announcements.
Your radio will play the traffic announcement even if the
volume is low. Your radio will interrupt the play of a
cassette tape or CD if the last tuned station broadcasts
traffic announcements.
Radio Display
Message
XL (Explicit Language
Channels)
Updating
No Signal
3-94
XM™ Radio Messages
Condition
XL on the radio display,
after the channel name,
indicates content with
explicit language.
Updating encryption
code
Loss of signal
This function does not apply to XM™ Satellite Radio
Service.
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.
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 your receiver is being updated, and
no action is required. This process should take no longer
than 30 seconds.
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.