Cadillac 2001 DeVille Owner's Manual page 349

Headlamp Horizontal Aiming
Turn the horizontal aiming screw (A) until the
indicator (B) is lined up with zero.
Once the horizontal aim is adjusted, then adjust the
vertical aim.
Headlamp Vertical Aiming
1. Find the aim dot on the lens of the 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.
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