Cadillac 2006 CTS Owner's Manual page 324

Headlamp aiming is done with the vehicle's low-beam
headlamps. The high-beam headlamps will be correctly
aimed if the low-beam headlamps are aimed properly.
To adjust the vertical aim, do the following:
1. Open the hood. See Hood Release on page 5-11
for more information.
2. Locate 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.
5-50
4. At the wall measure from the ground upward (A) to
the recorded distance from Step 3 and mark it.
5. Draw or tape a horizontal line (B) the width of the
vehicle at the wall where it was marked it Step 4.
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.