Pontiac 2006 GTO Owner's Manual page 234

To adjust the vertical aim on the headlamps, do the
following:
1. Open the hood. See Hood Release on page 5-11
for more information.
2. Find the aim dot on the lens of the low-beam
headlamp.
3. Measure the distance from the ground to the aim
dot on the low-beam headlamp. Record the
distance.
4. At the wall or other flat surface, measure from the
ground upward the recorded distance from Step 2
and mark it.
5. Draw or tape a horizontal line the width of the
vehicle at the wall or other flat surface where it
was marked it Step 4.
5-44
Notice: Do not cover a headlamp to improve beam
cut-off when aiming. Covering a headlamp may
cause excessive heat build-up which may cause
damage to the headlamp.
6. Turn on the low-beam headlamps and place a
piece of cardboard or equivalent in front of the
headlamp not being aimed. This should allow only
the beam of light from the headlamp being
aimed to be seen on the flat surface.
7. Locate the vertical headlamp aiming screws, which
are under the hood near each headlamp assembly.
The adjustment screw can be turned with a
No. 2 Phillips head screwdriver.