Installing Fog Lights on a Base Model 1999 GMC Sierra 1500 storeboard.com

Before installing any auxiliary lighting, however, you must address the condition of your truck’s factory headlights. On a 1999 GMC Sierra 1500, the original composite headlight lenses are now over 25 years old. Prolonged exposure to UV radiation, road salts, and temperature extremes causes the polycarbonate plastic to oxidize, turning from clear to a hazy, yellowed, and scratched surface. Driving a base model Sierra with severely degraded headlights is risky: diminished light output can reduce nighttime visibility by more than 50 percent, meaning you may not see pedestrians, animals, or road debris until it is too late. Installing fog lights while your 1999 GMC Sierra headlights remain cloudy is like putting a powerful flashlight behind a dirty window—you will still struggle to see clearly.