Upgrading from halogen to LED headlights is one of the highest-impact visibility improvements you can make to a fleet truck. Modern LED assemblies draw less current, run cooler, and project a tighter beam pattern that reduces fatigue on long night routes.
Before you start, confirm the new housing matches your truck's bulb clock position and connector type. Most Class 6–8 trucks use a 3-pin H4-style plug, but some newer models ship with a proprietary harness adapter — check the parts listing before ordering.
Disconnect the batteries first. Even with the ignition off, the headlight circuit can carry enough residual current to arc when you unplug the old housing. Remove the retaining screws, pull the old assembly straight out, and disconnect the harness.
Plug the LED assembly into the harness and seat it in the bucket. Reinstall the retaining screws hand-tight, then torque to the manufacturer spec — over-tightening warps the housing and breaks the weather seal.
Aiming is the step most fleets skip. Park the truck 25 feet from a flat wall on level ground, measure the headlight center height, and adjust the vertical screw until the beam's hot spot sits two inches below that height. Horizontal aim should keep the beam's left edge inside the truck's width to avoid blinding oncoming traffic.
Finish by resealing the housing-to-bucket seam with a thin bead of dielectric silicone. A failed seal is the #1 cause of LED condensation failures within the first year.