GMC 2007 Sierra 1500 Pickup Owner's Manual page 301

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 GM dealer for service.
LOCKED: This message is displayed when the
®
THEFTLOCK system has locked up. Take
the vehicle to your GM dealer for service.
If any error occurs repeatedly, or if an error cannot
be corrected, contact your GM dealer.
Radio Messages for XM™ Only
See XM Radio Messages on page 332 later in this
section for further detail.
Playing a CD
Insert a CD part way into the slot, label side up.
The player will pull 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 will stay in the player. When the
ignition or radio is turned on, the CD will
start playing where it stopped, if it was the last
selected audio source.
When a CD is inserted, the CD symbol will appear
on the display. As each new track starts to play,
the track number will appear 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 352 for more information.
If there is no apparent damage, try a known
good CD.
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