However, here's a general overview of how to adjust headlights, assuming you have access to the adjustment screws:
What you'll need:
* A flat-head screwdriver (possibly Phillips, depending on your vehicle): Used to adjust the screws.
* A flat, level surface: Essential for accurate adjustment.
* Measuring tape (optional but helpful): To ensure proper height.
* A wall or surface to project the light onto: This should be a minimum of 25 feet away from your vehicle. A garage door works well.
Steps:
1. Park on a level surface: Make sure your truck or Suburban is parked on a level surface about 25 feet away from a wall or other suitable surface. Ensure the vehicle is properly loaded (fuel, passengers, cargo) to simulate normal driving conditions. A slightly heavier load will slightly lower the beam.
2. Turn on your headlights: Turn on your low-beam headlights.
3. Locate the headlight adjustment screws: These are usually located on the back of the headlight housing. You may need to remove a cover or access panel to reach them. They will typically be marked with a diagram showing vertical and horizontal adjustment. One screw controls vertical adjustment (up and down), and another controls horizontal adjustment (left and right).
4. Adjust the vertical aim: This is the most important adjustment. The beam should be aimed slightly downward to avoid blinding oncoming drivers. Your owner's manual might specify the exact height (e.g., a certain number of inches from the ground at a certain distance). Aim for a slightly downward angle. Turning the screw clockwise usually raises the beam, and counter-clockwise lowers it.
5. Adjust the horizontal aim: This adjusts the left-to-right aiming of the headlights. Both headlights should be aimed in roughly the same direction. Make small adjustments, checking frequently against your wall or surface.
6. Check your adjustments: After making adjustments, check the headlight beams on your chosen surface. They should be aligned to produce a smooth, even light pattern. The cutoff line (the sharp edge of the light beam) should be relatively horizontal and even. The bright spot should be concentrated in the centre.
7. Repeat as needed: Make small adjustments until the beams are properly aligned.
8. Verify alignment: After making all the adjustments, check both headlights from a distance to make sure they are symmetrical and that the light pattern is even.
Important Considerations:
* Owner's Manual: Your owner's manual is the best resource for specific instructions for your vehicle year and model. The location and type of adjustment screws, as well as the proper aim, may vary.
* Professional Adjustment: If you're uncomfortable making these adjustments yourself, take your vehicle to a qualified mechanic or auto repair shop. They have the proper tools and experience to ensure accurate headlight alignment.
* Burned-out bulbs: Make sure both bulbs are functioning correctly before adjusting. A burned-out bulb will obviously affect the aim.
Remember: Improperly adjusted headlights can be dangerous. If you are unsure about any step, consult a professional.
