1998 Cadillac DeVille Owner's Manual - Page 327

2. Check the vertical headlamp aim first. Keep in mind 3. After the vertical aim is correct, check the horizontal that your vehicle needs be on a level surface. Turn to aim for each headlamp and adjust as necessary. Turn the vertical aiming screw until the bubble inside the the horizontal aiming screw until the end of the "0." level is centered at "0." screw aligns with the 4. Recheck the vertical aimto make sure it remains correct after the horizontal aim adjustment. Adjust as necessary. 6-40