2005 GMC Envoy Owner's Manual - Page 261

SEEK: Press this button to advance to the next station or track and stay there. The display will show the selection. This function is inactive if the front seat passengers are listening to the same audio source. To scan preset stations, press and hold the SEEK button for two seconds and the radio will advance to the next preset station. If you continue to hold the button down, the radio will continue to advance through the available preset stations. The display will show the selections. This function is inactive if the front seat passengers are listing to the radio. When a cassette tape is playing, press the SEEK button to go to the next selection on the tape. Press and hold the SEEK button to go to the other side of the tape. This function is inactive if the front seat passengers are listening to a cassette tape. When a CD is playing, press the SEEK button to go to the next track on the CD. This function is inactive if the front seat passengers are listening to a CD. When a CD is playing in the six-disc CD player, press and hold the SEEK button for 2 seconds to go you to the next CD, if multiple CDs are loaded. This function is inactive if the front seat passengers are listening to a CD. Theft-Deterrent Feature THEFTLOCK® is designed to discourage theft of your vehicle's radio. The feature works automatically by learning a portion of the Vehicle Identification Number (VIN). If the radio is moved to a different vehicle, it will not operate and LOCKED will appear on the display. When the radio and vehicle are turned off, the blinking red light indicates that THEFTLOCK® is armed. With THEFTLOCK® activated, the radio will not operate if stolen. 3-125