2002 Cadillac DeVille Owner's Manual - Page 209

Rear Window Defogger The grid lines you see on the rear window warm the glass. When the rear window defogger is turned on, the rear window and both outside rearview mirrors are heated to remove snow and ice from the surface of the glass. REAR (Rear Window Defogger): The rear window defogger button is located on the climate control panel near the bottom left corner. Press the button to turn on the rear defogger. Press the button again to turn the system off. The system will automatically shut off after 10 minutes unless your vehicle is traveling more than 30 mph (48 km/h). If further defogging is desired once the system is off, press the button again. The system will automatically shut off after five minutes for any cycles after the initial activation. NOTICE: Don't use a razor blade or something else sharp on the inside of the rear window. If you do, you could cut or damage the warming grid or the integrated rear window antenna, and the repairs wouldn't be covered by your warranty. The lines along the top of the window are for the diversity antenna and are not intended to defog the rear window. Do not attach a temporary vehicle license, tape or decals across the defogger grid on the rear window. 3-7