GMC 2007 Sierra 1500 Pickup Owner's Manual page 311

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 Cassette Tape
The tape player is built to work best with tapes
that are up to 30 to 45 minutes long on each side.
Tapes longer than that are so thin they may not
work well in this player. The longer side with
the tape visible should face to the right. If you hear
nothing or hear a garbled sound, the tape may not
be in squarely. Press the eject button to remove
the tape and start over.
If the ignition and radio are off, the tape can be
inserted, but will not play until ignition and
radio are on. If the ignition is on and the radio is
off, the tape can be inserted and will begin playing.
While the tape is playing, use the VOL, AUDIO,
and SEEK controls just as you do for the
radio. The cassette tape symbol will appear on the
display and an arrow showing which side of the
tape is playing. The tape player will play the other
side of the tape when it reaches the end.
Cassette tape adapter kits for portable CD players
will work in the cassette tape player. See "CD
Adapter Kits" later for more information.
The tape bias is set automatically when a metal or
chrome tape is inserted.
If an error appears on the display, see "Cassette
Tape Messages" later in this section.
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