2001 GMC Sierra 1500 Pickup Owner's Manual - Page 211

AM-FM: Press this button to switch from a tape to the radio. TAPE AUX: Press this button to return to the tape player when playing the radio. The lighted arrow will appear and show the direction of play when a tape is in the active mode. EJECT: Press this button to remove the tape. The radio will now play. EJECT can be used with either the ignition or radio off. To load a cassette tape with the ignition or radio off, press EJECT before loading the cassette. CLN: 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. After you clean the player, press and hold EJECT for five seconds to reset the CLN indicator. The radio will display --- to show the indicator was reset. CD Adapter Kits It is possible to use a portable CD player adapter kit with your cassette tape player after activating the bypass feature on your tape player. To activate the bypass feature, use the following steps: 1. Turn the ignition to RUN or ACCESSORY. 2. Turn the radio off. 3. Press and hold the TAPE AUX button for five seconds. The tape symbol on the display will flash for two seconds, indicating the feature is active. 4. Insert the adapter into the cassette slot. It will power up the radio and begin playing. This override routine will remain active until EJECT is pressed. 3-24