Mercedes-Benz 2009 M-Class Operator's Manual page 66

Safety and security
Occupant safety
Enhanced seat belt reminder system
When the engine is started, the seat belt
telltale will always illuminate for
<
6 seconds to remind you and your passengers
to fasten your seat belts.
If the driver's seat belt is not fastened when
the engine is started, an additional warning
chime will also sound for a maximum of
6 seconds or until the driver's seat belt is
fastened.
If after these 6 seconds the driver's or the
front passenger's seat belt (with the front
passenger seat occupied) is not fastened with
front doors closed,
the seat belt telltale remains
<
R
illuminated for as long as either the driver's
or front passenger's seat belt is not
fastened.
and if the vehicle speed once exceeds
R
15 mph (25 km/h), the seat belt telltale
starts flashing and a warning chime
<
sounds with increasing intensity for a
maximum of 60 seconds or until the
driver's and front passenger's seat belt are
fastened.
If you and/or your passenger release the
seat belt during driving, the seat belt
64
telltale starts flashing and the
<
warning chime sounds as described before.
If the driver's or the front passenger's seat
belt remains unfastened after 60 seconds,
the warning chime stops sounding, the seat
belt telltale stops flashing but
<
continues to be illuminated.
After a vehicle standstill, the warning chime
is reactivated and the seat belt telltale
is flashing again if the vehicle speed
<
once exceeds 15 mph (25 km/h).
The seat belt telltale will only go out if
<
both the driver's and the front passenger's
seat belt (with the front passenger seat
occupied) are fastened, or the vehicle is
standing still and a front door is opened.
For more information, see "Practical
hints" ( Y page 341).
Emergency Tensioning Device (ETD),
seat belt force limiter
The seat belts for the front seats and rear
outer seats are equipped with ETDs and seat
belt force limiters.
The ETDs are designed to activate in the
following cases:
in frontal or rear-end impacts exceeding
R
the system's preset deployment threshold
in side impacts exceeding the system's
R
preset deployment threshold on the far
side of the impact
in certain vehicle rollovers
R
if the restraint systems are operational and
R
functioning correctly, see
1
lamp ( Y page 47)
The ETDs for the front seats will only activate
if the front seat belts are fastened (latch plate
properly inserted into buckle).
The ETDs for the rear outer seats will activate
with or without the respective seat belts
fastened.
In an impact, the ETDs remove slack from the
seat belts in such a way that the seat belts fit
more snugly against the body. Seat belt force
limiters, when activated, are employed to
help reduce the peak force exerted by the
seat belts on occupants during a crash.
i The ETDs do not correct an incorrect seat
position or incorrectly worn seat belts.
The ETDs do not pull occupants back
toward the seat backrest.
indicator