1997 Pontiac Bonneville Owner's Manual - Page 150

Rear Window Defogger After 10 minutes it will turn off by itself or pressthe button during the heating cycle toturn it off. If you need additional warming time, push the button again. The system will then operate for five minutes before going off by itself. Do not attach a temporary vehicle license, tape or decals across the defogger grid on the rear window. NOTICE: The lines you see onthe r e a window warm the glass. Press the button to start warming your window. If you have the standard system, a light will glow in the switch while the defogger is working. Don't use a razor blade something else sharp or on the insideof the rear window. you do, you If could cut or damage warming grid, andthe the repairs wouldn't be covered your warranty. by 3-9