MERCEDES-BENZ R320 2008 W251 Owner's Manual

420 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
<The red seat belt telltale comes
on for a maximum of 6 seconds
after starting the engine.The seat belt telltale reminds you and your
passengers to fasten your seat belts before
driving off.Fasten your seat belts.
Regardless of whether the seat belts
are fastened or not, the seat belt tell-
tale always comes on and remains lit
for 6 seconds after starting the
engine.
<You hear a warning chime for a
maximum of 6 seconds after
starting the engine.You have forgotten to fasten your seat belt.Fasten your seat belt.
The warning chime stops sounding.
<The red seat belt telltale comes
on while the vehicle is standing
still and the engine is running or
during driving.You and/or your front passenger have for-
gotten to fasten your seat belts.Fasten your seat belts.
The seat belt telltale goes out.
There are items placed on the front passen-
ger seat and therefore the system senses the
front passenger seat as being occupied.Remove the items from the front pas-
senger seat and put them in a safe
place.
The seat belt telltale goes out.

421 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
<During driving the red seat belt
telltale flashes and you addition-
ally hear an intermittent warning
chime with increasing intensity.The vehicle’s speed once exceeded
15 mph (25 km/h) and you and/or your
front passenger have forgotten to fasten your
seat belts.Fasten your seat belts.
The seat belt telltale goes out and the
warning chime stops sounding.
There are items placed on the front passen-
ger seat and therefore the system senses the
front passenger seat as being occupied.Remove the items from the front
passenger seat and put them in a safe
place.
The seat belt telltale goes out and the
warning chime stops sounding.
iAfter 60 seconds with an unfastened seat
belt on one of the front seats, the warning chime
stops sounding and the seat belt telltale illumi-
nates continuously. The seat belt telltale will only
go out if both the driver and front passenger’s
seat belt are fastened, or the vehicle is standing
still and a front door is opened.

422 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
HUSA only:
Combination low tire
pressure/TPMS malfunction
telltale for the TPMS illuminates
continuously.
Canada only:
Low tire pressure telltale for the
Advanced TPMS* illuminates
continuously.The TPMS (USA only) or Advanced TPMS*
(Canada only) detects a loss of pressure in at
least one tire.Carefully bring the vehicle to a
halt, avoiding abrupt steering and
braking maneuvers. Observe the
traffic situation around you.
Read and observe messages in
the multifunction display.
If the tire inflation pressure in the
respective tire(s) has (have) been
corrected, the combination low tire
pressure/TPMS malfunction telltale
goes out after few minutes driving.
HUSA only:
Combination low tire
pressure/TPMS malfunction
telltale for the TPMS flashes
60 seconds and then stays
illuminated.There is a malfunction in the TPMS.Read and observe messages in
the multifunction display.
Have the TPMS checked by an
authorized Mercedes-Benz Light
Truck Center.
After the malfunction has been
remedied the combination low tire
pressure/TPMS malfunction telltale
goes out after few minutes driving.

423 Practical hints
What to do if …
Warning!G
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recom-
mended by the vehicle manufacturer on the
Tire and Loading Information placard on the
driver’s door B-pillar (
page 366) or, if
available, the tire inflation pressure label on
the inside of the fuel filler flap (
page 352).
If your vehicle has tires of a different size
than the size indicated on the Tire and
Loading Information placard or the tire
inflation pressure label, you should deter-
mine the proper tire inflation pressure for
those tires.
As an added safety feature, your vehicle has
been equipped with a tire pressure monitor-
ing system (TPMS) that illuminates a low tire
pressure telltale when one or more of your
tires is significantly underinflated. Accord-
ingly, when the low tire pressure telltale illu-
minates, you should stop and check your
tires as soon as possible, and inflate them to
the proper pressure. Driving on a signifi-
cantly underinflated tire causes the tire to
overheat and can lead to tire failure.
Underinflation also reduces fuel efficiency
and tire tread life, and may affect the vehi-
cle’s handling and stopping ability. Please
note that the TPMS is not a substitute for
proper tire maintenance, and it is the driv-
er’s responsibility to maintain correct tire
pressure, even if underinflation has not
reached the level to trigger illumination of
the TPMS low tire pressure telltale.USA only:
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate
when the system is not operating properly.
The TPMS malfunction indicator is com-
bined with the low tire pressure telltale.
When the system detects a malfunction, the
telltale will flash for approximately 1 minute
and then remain continuously illuminated.
This sequence will continue upon subse-
quent vehicle start-ups as long as the mal-
function exists. When the malfunction
indicator is illuminated, the system may not
be able to detect or signal low tire pressure
as intended.
TPMS malfunctions may occur for a variety
of reasons, including the installation of
replacement or alternate tires or wheels on
the vehicle that prevent the TPMS from
functioning properly. Always check the
TPMS malfunction telltale after replacing
one or more tires or wheels on your vehicle
to ensure that the replacement or alternate
tires and wheels allow the TPMS to continue
to function properly.

424 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
The yellow fuel tank reserve warning lamp in
the fuel gauge comes on while driving.The fuel level has gone below the reserve mark.Refuel at the next gas station
(
page 352).
1The red SRS indicator lamp comes
on while driving.There is a malfunction in the restraint systems.
The air bags or Emergency Tensioning Device
(ETDs) could deploy unexpectedly or fail to
deploy unexpectedly in an accident.Drive with added caution to the
nearest authorized
Mercedes-Benz Light Truck
Center.
Warning!G
In the event a malfunction of the SRS is indi-
cated as outlined above, the SRS may not be
operational. For your safety, we strongly
recommend that you contact an authorized
Mercedes-Benz Light Truck Center immedi-
ately 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 unexpect-
edly and unnecessarily which could result in
an accident and/or injury to you or to
others.

425 Practical hints
What to do if …
Lamp in center console
ProblemPossible cause/consequenceSuggested solution
59The front passenger
front air bag off indica-
tor lamp illuminates
and remains illuminat-
ed with the weight of a
typical adult or some-
one larger than a small
individual on the front
passenger seat.The system is malfunctioning.Have the system checked as soon as
possible by an authorized
Mercedes-Benz Light Truck Center.
Also read and observe any messages
in the multifunction display and follow
corrective steps (
page 438).
Warning!G
If the59indicator lamp
illuminates and remains illuminated with the
weight of a typical adult or someone larger
than a small individual on the front passen-
ger seat, do not have any passenger use the
front passenger seat until the system has
been repaired.

426 Practical hints
What to do if …
ProblemPossible
cause/consequenceSuggested solution
59The front passenger
front air bag off indica-
tor lamp does not illu-
minate and/or does
not remain illuminated
with the weight of a
typical 12-month-old
child in a standard
child restraint or less
on the front passenger
seat.The system is malfunction-
ing.Make sure there is nothing between seat cushion and
child seat and check installation of the child seat.
Make sure no objects applying supplemental weight
onto the seat are present.
Make sure no objects which apply forces to the seat
are present (e.g. objects such as books, briefcases
etc. lodged behind or around the seat, head restraints
pushing against roof etc.). The system may recognize
such forces as supplemental weight.
If the front passenger front air bag off indicator lamp
remains out, have the system checked as soon as pos-
sible by an authorized Mercedes-Benz Light Truck
Center. Do not transport a child on the front passen-
ger seat until the system has been repaired.
Also note any messages in the multifunction display
and follow corrective steps (
page 438).
Warning!G
If the59indicator lamp does
not illuminate or remains out with the
weight of a typical 12-month-old child in a
standard child restraint or less on the front
passenger seat, do not transport a child on the front passenger seat until the system
has been repaired.

427 Practical hints
What to do if …
Vehicle status messages in the
multifunction display
Warning and malfunction messages
appear in the multifunction display located
in the instrument cluster.
Certain warning and malfunction messag-
es are accompanied by an audible signal.
Address these messages accordingly and
follow the additional instructions given in
this Operator’s Manual.
Selecting the vehicle status message
memory menu in the control system
(
page 169) displays both cleared and
uncleared messages.
High-priority messages appear in the
multifunction display in red color.Certain messages of high priority cannot
be cleared from the multifunction display
using the reset button (
page 154) or
buttonj,k,ÿ, orè on the
multifunction steering wheel.
Other messages of high priority and mes-
sages of less immediate priority can be
cleared from the multifunction display
using the reset button (
page 154) or
buttonj,k,ÿ, orè on the
multifunction steering wheel. They are
then stored in the vehicle status message
memory (
page 169). Remember that
clearing a message will only make the mes-
sage disappear. Clearing a message will
not correct the condition that caused the
message to appear.
Warning!G
All categories of messages contain
important information which should be
taken note of and, where a malfunction is
indicated, addressed as soon as possible at
an authorized Mercedes-Benz Light Truck
Center.
Failure to repair condition noted may cause
damage not covered by the Mercedes-Benz
Limited Warranty, or result in property dam-
age or personal injury.

428 Practical hints
What to do if …
On the pages that follow, you will find a
compilation of the most important warning
and malfunction messages that may
appear in the multifunction display.
For your convenience the messages are
divided into two sections:

Text messages (page 429)

Symbol messages (page 444)
Warning!G
No messages will be displayed if either the
instrument cluster or the multifunction
display is inoperative.
As a result, you will not be able to see infor-
mation about your driving conditions, such
as speed or outside temperature, warn-
ing/indicator lamps, malfunction/warning
messages or the failure of any systems.
Driving characteristics may be impaired.
If you must continue to drive, do so with
added caution. Contact an authorized
Mercedes-Benz Light Truck Center as soon
as possible.
iSwitching on the ignition causes all
instrument cluster lamps (except high beam
headlamp indicator lamp, and turn signal indica-
tor lamps unless activated) as well as the multi-
function display to come on. Make sure the
lamps and multifunction display are in working
order before starting your journey.

429 Practical hints
What to do if …
Text messages
Display messagePossible cause/consequencePossible solution
ABSABS, ESP Inoperative
See Operator's ManualThe ABS and the ESP® have been
switched off due to a malfunction.
The BAS is also switched off.
The brake system is still functioning
normally but without the ABS avail-
able.Continue driving with added caution.
Wheels may lock during hard braking,
reducing steering capability.
Have the system checked at an authorized
Mercedes-Benz Light Truck Center as soon
as possible.
Failure to follow these instructions increases
the risk of an accident.
ABS, ESP Unavailable
See Operator’s ManualThe ABS and the ESP® have been
switched off because of insufficient
power supply. The charging voltage
has fallen below 10 volts.
The BAS is also switched off.
The brake system is still functioning
normally but without the ABS
available.When the voltage is above this value again, the
ABS is operational again and the message in
the multifunction display should disappear.
If the message in the multifunction display
does not disappear:
Have the system checked at an authorized
Mercedes-Benz Light Truck Center as soon
as possible.