GMC 2007 Sierra 1500 Pickup Owner's Manual page 351

The tape player should be cleaned regularly after
every 50 hours of use. The radio may display
CLEAN to indicate that the tape player has been
used for 50 hours without resetting the tape
clean timer. If this message appears on the
display, the cassette tape player needs to be
cleaned. It will still play tapes, but it should
be cleaned as soon as possible to prevent damage
to the tapes and player. If there is a reduction in
sound quality, try a known good cassette to
see if the tape or the tape player is at fault. If this
other cassette has no improvement in sound
quality, clean the tape player.
For best results, use a scrubbing action,
non-abrasive cleaning cassette with pads which
scrub the tape head as the hubs of the cleaner
cassette turn. The recommended cleaning cassette
is available through your dealer.
When cleaning the cassette tape player with the
recommended non-abrasive cleaning cassette, it is
possible that the cassette may eject, because
the cut tape detection feature on the radio
may recognize it as a broken tape, in error. To
prevent the cleaning cassette from being ejected,
use the following steps:
1. Turn the ignition on.
2. Turn the radio off.
3. Press and hold the TAPE DISC button for
five seconds. READY will appear on the
display and the cassette symbol will flash for
five seconds.
4. Insert the scrubbing action cleaning cassette.
5. Eject the cleaning cassette after the
manufacturer's recommended cleaning time.
When the cleaning cassette has been ejected,
the cut tape detection feature will be active
again.
351