GMC 2007 Yukon XL Owner's Manual page 477

7. Locate the vertical headlamp aiming screws,
which are under the hood near each headlamp
assembly.
The adjustment screw can be turned with a
®
E8 Torx socket.
8. Turn the vertical aiming screw until the
headlamp beam is aimed to the horizontal
tape line. Turn it clockwise or
counterclockwise to raise or lower the angle
of the beam.
9. Make sure that the light from the headlamp is
positioned at the bottom edge of the horizontal
tape line. The lamp on the left (A) shows
the correct headlamp aim. The lamp on the
right (B) shows the incorrect headlamp aim.
10. Repeat Steps 7 through 9 for the opposite
headlamp.
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