2005 Cadillac DeVille Owner's Manual - Page 317

Headlamp aiming is done with the vehicle low-beam lamps. The high-beam lamps will be correctly aimed if the low-beam lamps are aimed properly. The headlamp aiming devices are located under the hood near the headlamps. Headlamp Horizontal Aiming If your vehicle has the horizontal aim indicators, turn the horizontal aiming screw (A) until the indicator (B) is lined up with zero. If you believe your headlamps need horizontal (left/right) adjustment, follow the horizontal aiming procedure. If you believe your headlamps need only vertical (up/down) adjustment, follow only the vertical aiming procedure. Once the horizontal aim is adjusted, then adjust the vertical aim. 5-49