Adjust your GM headlights by turning the vertical and horizontal adjustment knobs, located on the upper-rear cornets of the headlight housings. GM headlights should be aimed to give the driver the greatest field of vision without blinding incoming traffic.
To aim your headlights properly, ensure that the fuel tank is full and that all tires are properly inflated according to the manufacturer's recommendation. Additionally, ensure that there is not any significant suspension issue that may cause a side of the vehicle to sag. Park the vehicle a few inches away from a light-colored wall that is free from other light sources. Using tape, make a cross on the wall at the same location as the centerline of the low-beam headlights.
After marking the beam centerlines, carefully reverse the car until there is a distance of 25 feet between the headlights and the wall. With the low beams turned on, locate the point where the hot spots rest. Using the horizontal and vertical adjustment knobs, adjust the headlights until the hot spots rest 2 inches below and to the right of the low beams' centerlines. Re-aim the headlights each time you change a bulb, or when a vehicle is carrying a substantial amount of weight.