GMC Sierra Classic 2007 Owner's Manual page 297

Radio Messages
CAL ERR (Calibration Error): The audio system
has been calibrated for your vehicle from the
factory. If CAL ERR appears on the display, it
means that the radio has not been configured
properly for the vehicle and must be returned to
your dealer for service.
LOCKED: This message is displayed when the
®
THEFTLOCK system has locked up. Take
the vehicle to your dealer for service.
If any error occurs repeatedly, or if an error cannot
be corrected, contact your dealer.
Radio Messages for XM™ Only
See XM Radio Messages on page 327 later in this
section for further detail.
Playing a CD
Insert a CD part way into the slot, label side up. The
player pulls it in and the CD should begin playing. If
you want to insert a CD with the ignition off, first
press the eject button or the INFO knob.
If the ignition or radio is turned off with the CD in
the player, it stays in the player. When the
ignition or radio is turned on, the CD starts playing
where it stopped, if it was the last selected
audio source.
When a CD is inserted, the CD symbol appears
on the display. As each new track starts to
play, the track number appears on the display.
The CD player can play the smaller 3 inch (8 cm)
single CDs with an adapter ring. Full-size CDs
and the smaller CDs are loaded in the same
manner.
If playing a CD-R, the sound quality may be
reduced due to CD-R quality, the method of
recording, the quality of the music that has been
recorded, and the way the CD-R has been
handled. There may be an increase in skipping,
difficulty in finding tracks, and/or difficulty in loading
and ejecting. If these problems occur, check the
bottom surface of the CD. If the surface of the CD
is damaged, such as cracked, broken, or
scratched, the CD will not play properly. If the
surface of the CD is soiled, see Care of Your CDs
and DVDs on page 347 for more information.
If there is no apparent damage, try a known
good CD.
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