1996 Pontiac Firebird Owner's Manual - Page 141
1996 Pontiac Firebird Manual
Page 141 highlights
Rear Window Defogger (Option) - The rear window defogger uses a warming grid to remove fog from the rear window. Do not attach anything like a temporary vehicle license 1 or a decal across the defogger grid on the rear window. NOTICE: Don't use a razor blade or something else sharp on the insideof the rearwindow. If you do, you could cut or damage the warming grid, and the repairs wouldn't be covered by your warranty. Press the switch to turn on the defogger. An indicator light will come on to remind you that the defogger is on. The defogger will turn off automatically after about 10 minutes of use. If you turn it on again, the defogger will operate for about five minutes only. You can also turn the defogger off by pressing the switch again. 3-4