2002 GMC Savana Van Owner's Manual - Page 147

Rear Window Defogger (If Equipped) If you see lines running across the rear windows, your vehicle has a rear window defogger. The lines warm the glass. For best results, clear the windows of as much snow or ice as possible before using the rear window defogger. To turn on the rear window defogger, press this button located near the fan control. An indicator light in the button will come on when the rear window defogger is working. The rear window defogger will turn itself off after several minutes. If you need additional warming time, press the button again. Pressing the button when the indicator light is illuminated will turn the defogger off. If your vehicle is equipped with heated outside rearview mirrors, the rear window defogger button will activate both the rear window defogger and the heated outside rearview mirrors. See "Heated Outside Rearview Mirrors" in the Index. Do not attach a temporary vehicle license, tape or decals across the defogger grid on the rear windows. Use care not to damage the wiring bands that connect the rear window defogger grid when operating the rear swing-out windows (if equipped). NOTICE: The rear window defogger will only work when the ignition is in RUN. 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, and the repairs wouldn't be covered by your warranty. 3-8