2008 GMC Sierra 1500 Pickup Owner's Manual - Page 362

To adjust the vertical aim: 1. Open the hood. See Hood Release on page 5-11 for more information. 4. At a 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) on the wall the width of the vehicle at the height of the mark in Step 4. 2. Locate the aim dot on the lens of the low-beam headlamp. 3. Record the distance from the ground to the aim dot on the low-beam headlamp. 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 adjusted. This allows only the beam of light from the headlamp being adjusted to be seen on the flat surface. 5-50