How do you adjust headlights on a 1990 gmc sierra?

Answer 1

First you should take a 5 millimeter socket and remove the two screws that stand up kind of obvious on/above the sheet metal right above the headlights, then pull out the entire headlight assembly. Then put some oil on the adjuster screw assemblies, attached to headlight assembly, and clean them with a wire brush if they need it. Including the two threaded rods.

You can adjust the headlights by turning the two screws which have a Torx bit hole in the end, which is a T-15 on my truck. The adjuster screw mechanisms rotate around a small threaded rod, which is held still, so the partialy-hidden piece that rotates around the rod needs to be covered in oil to maintain it's freedom of movement.

Once the headlight assembly is put back in place (oil the threads on the two long mount screws), you can access the adjuster screws down through two holes in the sheet metal above them. You will need either a long torx tool, like a t-handle, or use a torx bit on a long bit-holder extension. (About 3 inches down in the holes.)

They are visble with a flashlight down through the holes on top. Try turning these adjuster screws first, because if they turn easily and without a fuss then they may not need cleaning and lubrication. Though they usually do, given the age of the vehicles in question.