Before Checking the Headlight
Aim
Before checking or adjusting the headlight aim, do
the following:
•
Check that the hood is closed and latched.
•
Check the suspension for proper functioning of
the leveling mechanism. On cabs with air
suspensions, make sure that the height is
properly adjusted.
•
If necessary, remove any large amounts of
mud or ice from the underside of the fenders.
•
Check the springs for sagging or broken
leaves.
•
Check for damage to the hood and hinge
assembly. Repair as necessary.
•
With the vehicle unloaded, check that the tires
are inflated to the recommended air pressure.
•
Clean the headlight lenses. Use a soft cloth
with mild, non-caustic soap or detergent, and
water.
Checking Headlight Aim
1.
Park the vehicle on a level surface, 25 ft (7.6 m)
away from, and perpendicular to, a vertical
screen or wall. Shut down the engine and set the
parking brake. Chock the tires.
2.
Each headlight has a height adjusting dot. See
Fig. 18.1. Measure the distance from the ground
to the height adjusting dot on each headlight.
Note those distances. See
Fig. 18.2, Ref. A.
3.
Mark the vertical distances found in step 2 on
the screen or wall, directly in front of the
headlights. These marks represent the desired
locations of each headlight bulb center in the
following steps. See
Fig. 18.2, Items 2 and 3.
4.
Turn on the low-beam headlights.
5.
Identify the center of each beam projection by
marking the area of brightest intensity on the
wall. The area of brightest intensity should fall on
or very near the marks made during step 3. See
Fig. 18.3.
6.
Use Table 18.1 to determine the maximum
vertical distance allowable between the marks
made in step 3 and the marks made in step 5. If
the vertical distance between the marks made in
steps 3 and 5 is greater than the maximum
distance given in
Table 18.1, adjust the vertical
positioning of that headlight.
Adjusting Headlight Aim
NOTICE
Do not use power tools to adjust headlight aim.
Doing so will strip or break the adjusting screw.
1.
Lift up the splash shield to expose the adjusting
knob shown in Fig. 18.4.
2.
Turn the adjusting screw clockwise to raise the
beam of the headlight or counterclockwise to
lower it.
3.
If necessary, adjust the other headlight.
11/06/2002 f544236
Measure beam height from the ground to the small dot
roughly in the center of the headlight lens.
Fig. 18.1, Headlight Beam Height Adjusting Dot
Headlight Aiming
18.1
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