GMC 2003 C4C042 Owner's Manual page 185

Cassette Tape Messages
ERR (Error): If the player detects a tight or broken
tape, this message will appear on the display and the
player will eject the tape. The radio will go back to
playing the last station selected.
CLN (Clean): If this message appears on the display,
the cassette tape player needs to be cleaned. It will still
play tapes, but you should clean it as soon as possible to
prevent damage to the tapes and player. See "Care of
Your Cassette Tape Player" in the Index.
3-16
CD Adapter Kits
It is possible to use a portable CD player adapter kit
with your cassette tape player after deactivating the
tight/loose tape sensor feature on your tape player.
To deactivate this feature, use the following steps:
1. Turn the ignition to RUN or ACCESSORY.
2. Turn the radio off.
3. Press and hold the TAPE button for two seconds
until one beep is produced. CAS will flash on the
display, showing that the TIGHT/LOOSE TAPE
sensor is no longer active.
4. Insert the adapter into the cassette slot.
The override feature will remain active until the eject
button is pressed.