GMC 2012 Sierra Series Owner's Manual page 440

10-40 Vehicle Care
The vehicle should:
Be placed so the headlamps
are 7.6 m (25 ft) from a
light colored wall.
Have all four tires on a level
surface which is level all the way
to the wall.
Be placed so it is perpendicular
to the wall.
Not have any snow, ice, or mud
on it.
Be fully assembled and all other
work stopped while headlamp
aiming is being performed.
Be loaded with a full tank of fuel
and one person or 75 kg
(160 lbs) sitting on the
driver seat.
Have the tires properly inflated.
Have the spare tire in its proper
location in the vehicle.
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:
1. Open the hood. See Hood on
page 10 5
2. Locate the aim dot on the lens of
the low beam headlamp.
I n f o r ma t i o n P r o v i d e d b y :
3. Record the distance from the
ground to the aim dot on the
low beam headlamp.
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.