Pontiac 2000 Bonneville Owner's Manual page 311

Headlamp Vertical Aiming
1. Find the aim dot on the lens of the lamps.
2. Measure the distance from the ground to the aim dot
on each lamp; if left low beam, subtract two inches.
Record this distance.
3. At the wall or other flat surface, measure from the
floor to the recorded distance and draw a horizontal
line the width of the vehicle.
6-36
4. Turn on the low beam headlamps and cover the lamp
not being evaluated. The ambient light should allow
the beam cut off to be seen on the wall.