Pontiac 2002 Bonneville Owner's Manual page 334

If you believe your headlamps need horizontal
(left/right) adjustment, follow the horizontal aiming
procedure. If you believe your headlamps need only
vertical (up/down) adjustment, follow only the vertical
aiming procedure.
Adjustment screws can be turned with an E8 Torx
socket or T15 Torx screwdriver.
Headlamp Horizontal Aiming
Turn the horizontal aiming screw (A) until the
indicator (B) is lined up with zero.
Once the horizontal aim is adjusted, then adjust the
vertical aim.
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