2004 GMC Sonoma Owner's Manual - Page 157

If the radio cannot find the desired program type, NONE will appear on the display and the radio will return to the last station you were listening to. BAND (Alternate Frequency): Alternate frequency allows the radio to switch to a stronger station with the same program type. To turn alternate frequency on, press and hold BAND for two seconds. AF ON will appear on the display. The radio may switch to stronger stations. To turn alternate frequency off, press and hold BAND again for two seconds. AF OFF will appear on the display. The radio will not switch to other stations. ALERT! will not be affected by tests of the emergency broadcast system. This feature is not supported by all RDS stations. INFO (Information): If the current station has a message, the information symbol will appear on the display. Press this button to see the message. The message may display the artist, song title, call in phone numbers, etc. If the whole message is not displayed, parts of the message will appear every three seconds. To scroll through the message at your own speed, press the INFO button repeatedly. A new group of words will appear on the display with each press. Once the complete message has been displayed, the information symbol will disappear from the display until another new message is received. The old message can be displayed by pressing the INFO button. You can view an old message until a new message is received or a different station is tuned to. When a message is not available from a station, NO INFO will appear on the display. RDS Messages ALERT!: Alert warns of local or national emergencies. When an alert announcement comes on the current radio station, ALERT! will appear on the display. You will hear the announcement, even if the volume is muted or a cassette tape or CD is playing. If a cassette tape or CD is playing, play will stop during the announcement. You will not be able to turn off alert announcements. 3-53