2004 Cadillac DeVille Owner's Manual - Page 332

Headlamp Vertical Aiming Notice: Horizontal aiming must be performed before making any adjustments to the vertical aim. Adjusting the vertical aim first will result in an incorrect headlamp aim. 1. Find the aim dot on the lens of the low beam lamps. 2. Measure the distance from the ground to the aim dot on each lamp; if left low beam, subtract two inches. Record this distance. 3. At the wall or other flat surface, measure from the ground upward the recorded distance from Step 2 and draw or tape a horizontal line the width of the vehicle. 5-52