belt MERCEDES-BENZ M320 2000 W163 User Guide

49 Restraint systems
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cluster displayPractical hints Car care Index Tighten the lap portion to a snug fit by pulling shoulder
portion up.
The shoulder portion of the seat belt must be pulled
snug and checked for snugness immediately after
engaging it.
Adjust seat belt so that shoulder portion is located as
close as possible to the middle of your shoulder (it
should not touch the neck). For this purpose, you can
adjust the height of the belt outlet. Three positions are
available.4Button for belt outlet height adjustment
To raise, slide belt height adjustment upward.
To lower, press button (4) and slide belt outlet
downward.
Caution!
For safety reasons, avoid adjusting the seat or backrest
into positions which could affect the correct seat belt
positioning.

50 Restraint systems
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Operation
The inertia reel stops the belt from unwinding during
sudden vehicle stops or when quickly pulling on the
belt. The locking function of the reel may be checked by
quickly pulling out the belt.
Unfastening of seat belts
Push the release button (3) in the belt buckle (2).
Allow the retractor to completely rewind the seat belt by
guiding the latch plate (1).
Wa r n i n g !
USE SEAT BELTS PROPERLY.• Seat belts can only work when used properly.
Never wear seat belts in any other way than as
described in this section, as that could result
in serious injuries in case of an accident.• Each occupant should wear their seat belt at all
times, because seat belts help reduce the
likelihood of and potential severity of injuries
in accidents, including rollovers. The
integrated restraint system includes “SRS”
(driver airbag, front passenger airbag, front
and rear door mounted side impact airbags),
“ETR” (seat belt emergency tensioning
retractors for the outboard passenger seats
[except in the optional 3rd row seats]), and
front seat knee bolsters. The system is
designed to enhance the protection offered to
properly belted occupants in certain frontal
(front airbags) and side (side impact airbags)
impacts which exceed preset deployment
thresholds.

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• Never wear the shoulder belt under your arm,
against your neck or off your shoulder. In a
crash, your body would move too far forward.
That would increase the chance of head and
neck injuries. The belt would also apply too
much force to the ribs or abdomen, which
could severely injure internal organs such as
your liver or spleen.• Never wear belts over rigid or breakable
objects in or on your clothing, such as
eyeglasses, pens, keys etc., as these might
cause injuries.• Position the lap belt as low as possible on your
hips and not across the abdomen. If the belt is
positioned across your abdomen, it could cause
serious injuries in a crash.
• Each seat belt should never be used for more
than one person at a time. Do not fasten a seat
belt around a person and another person or
other objects.• Belts should not be worn twisted. In a crash,
you wouldn’t have the full width of the belt to
manage impact forces. The twisted belt against
your body could cause injuries.• Pregnant women should also use a lap-
shoulder belt. The lap belt portion should be
positioned as low as possible on the hips to
avoid any possible pressure on the abdomen.• Never place your feet on the instrument panel
or on the seat. Always keep both feet on the
floor in front of the seat.

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Wa r n i n g !
USE CHILD RESTRAINTS PROPERLY.Children 12 years old and under must never ride in
the front seat, except in a Mercedes-Benz
authorized BabySmart
TM compatible child seat,
which operates with the BabySmart
TM system
installed in the vehicle to deactivate the passenger
front airbag when it is properly installed.
Otherwise they will be struck by the airbag when it
inflates in a crash. If this happens, serious or fatal
injury will result.
According to accident statistics, children are safer
when properly restrained in the rear seating
positions than in the front seating positions.
Infants and small children must ride in back seats
and be seated in an appropriate infant or child
restraint system, which is properly secured with
the vehicle’s seat belt, fully in accordance with the
child seat manufacturer’s instructions.
A child’s risk of serious or fatal injuries is
significantly increased if the child restraints are
not properly secured in the vehicle and the child is
not properly secured in the child restraint.Children too big for child restraint systems must
ride in back seats using regular seat belts. Position
shoulder belt across chest and shoulder, not face or
neck. A booster seat may be necessary to achieve
proper belt positioning.

54 Restraint systems
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Supplemental restraint system (SRS)
Airbags are intended as a supplement to seat belts.
Airbags alone cannot protect as well as airbags plus
seat belts in impacts for which the airbags were
designed to operate, and do not afford any protection
whatsoever in crashes for which the airbags are not
designed to deploy.
The SRS uses two crash severity levels (thresholds) to
activate either the Emergency Tensioning Retractor
(ETR) or front airbag or both. Activation depends on the
direction and severity of the impact exceeding the
preset thresholds and whether the seat belt is fastened.Seat belt fastened
•first threshold exceeded: ETR activates
•second threshold exceeded: airbag also activates
Seat belt not fastened
Front seats:
•first threshold exceeded:
airbag activates, but not ETR
Rear outer seats:
•first threshold exceeded:
ETR activates
Driver, front passenger and rear outer seat systems
operate independently of each other.

55 Restraint systems
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cluster displayPractical hints Car care Index Emergency tensioning retractor (ETR)
The seat belts for the outboard passenger seats (except
in the optional 3rd row seats) are equipped with
emergency tensioning retractors. These tensioning
retractors are located in each belt’s inertia reel and
become operationally ready with the key in steering
lock position 1 or 2.
The emergency tensioning retractors are designed to
activate only when the seat belts are fastened during
frontal impacts exceeding the first threshold of the SRS
and in rear impacts exceeding a preset severity level.
They remove slack from the belts in such a way that the
seat belts fit more snugly against the body restricting its
forward movement as much as possible.In cases of other frontal impacts, angled impacts, roll-
overs, certain side impacts, or other accidents without
sufficient frontal or rear impact forces, the emergency
tensioning retractors will not be activated. The driver
and passengers will then be protected by the fastened
seat belts and inertia reel in the usual manner.
For seat belt and emergency tensioning retractor see
page 63.

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Airbags
1Driver airbag
The most effective occupant restraint system yet
developed for use in production vehicles is the seat belt.
In some cases, however, the protective effect of a seat
belt can be further enhanced by an airbag.
The driver airbag is located in the steering wheel hub. 2Front passenger airbag
The passenger front airbag is located in the dashboard
ahead of the front passenger.

57 Restraint systems
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cluster displayPractical hints Car care Index 3Side impact airbag, front
The side impact airbags are located in the front and rear
doors.
In conjunction with wearing the seat belts, the driver
and front passenger airbags can provide increased
protection for the driver and front passenger in certain
frontal impacts exceeding preset thresholds.4Side impact airbag, rear
Door mounted side impact airbags can provide
increased protection to belted outboard occupants on
the impacted side of the vehicle in side impacts
exceeding its preset threshold.
Important!
The operational readiness of the airbag system is
verified by the indicator lamp “SRS” in the instrument
cluster when turning the key in steering lock to
position 1 or 2. If no fault is detected, the lamp will go
3

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out after approximately 5 seconds; after the lamp goes
out, the system continues to monitor the components
and circuitry of the airbag system and will indicate a
malfunction by coming on again. If the lamp does not
come on at all or if it fails to extinguish after
approximately 5 seconds or if it comes on thereafter,
a malfunction in the system has been detected.
The following system components are monitored or
undergo a self-check: crash-sensor(s), airbag ignition
circuits, front seat belt buckles, emergency tensioning
retractors, seat sensor.
Initially, when the key is turned from steering lock
position 0 to positions 1 or 2, malfunctions in the
crash-sensor are detected and indicated (the “SRS”
indicator lamp stays on longer than 5 seconds or does
not come on).
Have the system checked at your authorized
Mercedes-Benz Light Truck Center immediately.In the operational mode, after the indicator lamp has
gone out following the initial check, interruptions or
short circuits in the airbag ignition circuit and in the
driver and front passenger seat belt buckle harnesses,
and low voltage in the entire system are detected and
indicated.
Wa r n i n g !
In the event a malfunction of the “SRS” is indicated
as outlined above, the “SRS” may not be
operational. For your safety, we strongly
recommend that you visit an authorized
Mercedes-Benz Light Truck Center immediately to
have the system checked; otherwise the “SRS” may
not be activated when needed in an accident, which
could result in serious or fatal injury, or it might
deploy unexpectedly and unnecessarily which
could also result in injury.

59 Restraint systems
Te ch n ica l
data Instruments
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cluster displayPractical hints Car care Index Front airbags
The driver and front passenger front airbags are
designed to activate only in certain frontal impacts
exceeding a preset threshold.
The front passenger airbag deploys only if the front
passenger seat is occupied and the ü indicator lamp
in the instrument cluster is not illuminated.
Note:
Heavy objects on the front passenger seat can appear to
the “SRS” to indicate the presence of an occupant in
that seat which causes the passenger front airbag to
deploy in a crash exceeding the appropriate threshold.
Side impact airbags
The side impact airbags are designed to activate only in
certain side impacts exceeding a preset threshold. Only
the side impact airbags on the impacted side of the
vehicle deploy.
The side impact airbag for the front passenger deploys
only if the front passenger seat is occupied.
Side impact airbags operate best in conjunction with a
properly positioned and fastened seat belt.Note:
Heavy objects on front passenger seat can cause the
side impact airbag to deploy in a crash.
Important!
Airbags are designed to activate only in certain
frontal (front airbags) impacts, or side (side impact
airbags) impacts which exceed preset thresholds.
Only during these types of impacts, if of sufficient
severity to meet the deployment thresholds, will
they provide their supplemental protection.
The driver and passenger should always wear their
seat belts, otherwise it is not possible for the airbags
to provide their intended supplemental protection.
In cases of other frontal impacts, angled impacts,
roll-overs, other side impacts, rear collisions, or
other accidents in which the airbags are not
designed to deploy, the airbags will not be activated.
The driver and passenger will then be protected by
the fastened seat belts.
We caution you not to rely on the presence of the
airbags in order to avoid wearing your seat belt.