2004 GMC Envoy Owner's Manual - Page 201

If both PTY and TRAF are on, the radio will search for stations with the selected PTY and traffic announcements. 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. SCAN: Scan the stations within a PTY by performing the following: 1. Turn the P-TYPE knob to activate program type select mode. TYPE and a PTY will appear on the display. 2. Turn the P-TYPE knob to select a PTY. 3. Once the desired PTY is displayed, press either SCAN arrow, and the radio will begin scanning the stations in the PTY. 4. Press either SCAN arrow to stop scanning. If both PTY and TRAF are on, the radio will scan for stations with the selected PTY and traffic announcements. 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 stations with a stronger frequency. 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. This function does not apply for XM™ Satellite Radio Service. 3-81