2001 GMC Sierra 1500 Pickup Owner's Manual - Page 220

Tips About Your Audio System Hearing damage from loud noise is almost undetectable until it is too late. Your hearing can adapt to higher volumes of sound. Sound that seems normal can be loud and harmful to your hearing. Take precautions by adjusting the volume control on your radio to a safe sound level before your hearing adapts to it. To help avoid hearing loss or damage: NOTICE: Before you add any sound equipment to your vehicle -- like a tape player, CB radio, mobile telephone or two-way radio -- be sure you can add what you want. If you can, it's very important to do it properly. Added sound equipment may interfere with the operation of your vehicle's engine, Delphi Delco Electronics radio or other systems, and even damage them. Your vehicle's systems may interfere with the operation of sound equipment that has been added improperly. So, before adding sound equipment, check with your dealer and be sure to check Federal rules covering mobile radio and telephone units. D Adjust the volume control to the lowest setting. D Increase volume slowly until you hear comfortably and clearly. 3-33