Figure 4-6.—Typical sealed beam headlight assembly.
lights that outlines the height of the vehicle. Some
vehicles have a separate switch for the clearance lights.
When you are operating a vehicle at night with clearance
lights, do not forget to turn them on.
Side Marker Lights
Side marker lights are similar to clearance lights;
however; they indicate the full-overall length of the
vehicle as viewed from the side. They must also be
visible from a minimum distance of 500 feet from the
vehicle. Side marker lights, mounted near the front of
the vehicle, are also amber and those near the rear are
red.
Reflectors
Reflectors (except for those used in the lights) are
used as an additional safety precaution in case lights
burn out or are broken. When mounting reflectors,
ensure they are between 24 to 42 inches above the
ground.
Taillights and Brake Lights
All taillights must show red and be visible from at
least 500 feet from the rear of the vehicle. The taillight
lens should be replaced if it is not red or contains a dot
of another color or if it is cracked, broken, or does not
fit tightly. A brake light is usually combined with the
taillight by using a double-contact, double-filament
bulb; however, it maybe a separate light. Stop lights
must light up immediately when the brake pedal is
depressed; that is, at the beginning of the downward
action of the brake pedal. Brake lights are a
safety-required item and they must be operational at all
times. Burnt-out or weak lights should be documented
and repaired before operating your vehicle or piece of
equipment.
Auxiliary Lights
Lights that can be turned on or off for the
convenience or safety of the driver or passengers are
called auxiliary lights. These lights are wired to be
turned on and off independently, and not with the
headlights. When performing your prestart operation,
you should ensure all auxiliary lights work.
SPOTLIGHTS.— Spotlights are often mounted on
construction equipment and weight-handling
equipment. When conducting prestart operations,
always make sure the spot-lights work because you
never know when you will encounter conditions or
situations requiring their use.
BACKUP LIGHTS.— Backup lights are
accessories for many vehicles. They may be mounted
singly or as a pair, one on each side. Backup lights
lenses must be colorless and must turnoff automatically
when the vehicle is moving forward. Backup lights may
also be connected to a audible signal. A backup light
must be aimed to strike the road at a distance that does
not exceed 25 feet from the rear of the vehicle.
PARKING LIGHTS.— Parking lights have amber
or white lenses and are located on the front of the
vehicle. They turn on and off with the same switch as
the taillights.
Fuses
Fuses are safety devices placed in electrical circuits
to protect wires and electrical units from a heavy flow
of current. Each circuit, or at least each individual
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