MERCEDES-BENZ R350 2008 W251 Owner's Manual

440 Practical hints
What to do if …
Display messagePossible
cause/consequencePossible solution
Front Passenger Airbag
Disabled
See Operator’s ManualFront passenger front
air bag is deactivated
while driving even
though an adult or
someone larger than a
small individual is oc-
cupying the front pas-
senger seat. Forces
acting on the seat may
make the system
sense a decrease in
weight.Stop the vehicle in a safe location as soon as possible and check the front
passenger seat for the following:
Apply the parking brake (page 65).
Switch off the ignition (page 39).
Have the front passenger vacate the seat and exit the vehicle.
Adjust the seat in a height position (page 44).
Make sure that no objects which apply forces to the seat are present (e.g. ob-
jects such as books, briefcases etc. lodged underneath, behind or around the
seat). Such forces may cause the system to sense that an occupant of a lesser
weight than actually present is on the front passenger seat.
Keep the seat unoccupied, close the front passenger door and switch on the
ignition (
page 39).
(Continued on next page)

441 Practical hints
What to do if …
Display messagePossible
cause/consequencePossible solution
Monitor the 59indicator lamp on the center console (page 81) and
the multifunction display in the instrument cluster (
page 29) for the following:
With the seat unoccupied and the ignition turned on,

the 59indicator lamp on the center console should illuminate and
remain illuminated, indicating that the OCS (
page 77) has deactivated the air
bag.

the message Front Passenger Airbag Enabled See Operator’s Manual or the
message
Front Passenger Airbag Disabled See Operator’s Manual should
not appear in the multifunction display at any time the seat is unoccupied. Wait
at least 60 seconds for the system to complete the necessary check cycles and
to make sure neither message appears in the multifunction display.
If above conditions are met, you can occupy the front passenger seat again.
Depending on the front passenger classification sensed by the OCS (
page 77),
the 59indicator lamp will remain illuminated or go out.
If above conditions are not met, the system is not working properly. Have the
system checked as soon as possible by an authorized Mercedes-Benz Light Truck
Center.
Warning!G
If the 59indicator lamp re-
mains out even after performing the above
corrective steps, do not have any children
12 years old and under and other small individuals use the front passenger seat
until the system has been repaired.

442 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
Check tires,
then restart
Run Flat Indicator.
There was a warning message about
a loss in the tire inflation pressure
and the Run Flat Indicator has not
been reactivated yet.Make sure that the correct tire inflation pressure is set
for each tire.
Then restart the Run Flat Indicator (page 375).
Run Flat Indicator
InoperativeRun Flat Indicator is malfunctioning.Have the Run Flat Indicator checked by an authorized
Mercedes-Benz Light Truck Center.
Tire Pressure
Check TiresThe Run Flat Indicator indicates that
the pressure is too low in one or more
tires.Carefully bring the vehicle to a halt, avoiding abrupt
steering and braking maneuvers. Observe the traffic
situation around you.
Check and adjust tire inflation pressure as required
(
page 373).
If necessary, replace the wheel (page 492).
Restart the Run Flat Indicator after adjusting the tire
inflation pressure values (
page 375).
Tire pressure
displayed after
driving for
a few minutes
.
Vehicles with Advanced TPMS*:
The tire inflation pressure is being
checked.Drive the vehicle for a few minutes.

443 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
Tire Pressure Monitor
InoperativeThe TPMS or Advanced TPMS* is
malfunctioning.Have the TPMS or Advanced TPMS* checked by an
authorized Mercedes-Benz Light Truck Center.
Tire Pressure Monitor
Inoperative
No Wheel SensorsThere are wheels without appropriate wheel
sensors mounted (e.g. winter tires).Have the TPMS or Advanced TPMS* checked by an
authorized Mercedes-Benz Light Truck Center.
Have the wheel sensors installed by an authorized
Mercedes-Benz Light Truck Center.
Tire Pressure Monitor
Wheel Sensor MissingVehicles with Advanced TPMS*:
One or more sensors are defect (e.g.
battery is empty).
The respective tire is indicated by
---
instead of the tire inflation pressure in the
multifunction display.
Have the Advanced TPMS* checked by an autho-
rized Mercedes-Benz Light Truck Center.
Vehicles with Advanced TPMS*:
One or more wheels without appropriate
wheel sensors mounted (e.g. spare tire).
The respective tire is indicated by
---
instead of the tire inflation pressure in the
multifunction display.
Have the wheel sensors installed by an authorized
Mercedes-Benz Light Truck Center.
Tire Pressure Monitor
Currently UnavailableThe TPMS or Advanced TPMS* is unable to
monitor the tire pressure due to a nearby
radio interference source.As soon as the causes of the malfunction have been
removed, the TPMS or Advanced TPMS* automati-
cally becomes active again after a few minutes
driving.

444 Practical hints
What to do if …
Symbol messages
Display symbolDisplay messagePossible cause/consequencePossible solution
òReplace air filter.The air filter is clogged.Have the air filter checked by an autho-
rized Mercedes-Benz Light Truck Center.
#The battery is no longer charg-
ing.
Possible causes:

alternator malfunctioning

broken poly-V-belt
Do not forget that the brake
system requires electrical
energy and may be operating
with restricted capability.
Considerably greater brake
pedal force is required and the
stopping distance is increased.
Stop the vehicle in a safe location or as
soon as it is safe to do so and check the
poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine.
Contact an authorized
Mercedes-Benz Light Truck Center.
If it is intact:
Contact an authorized
Mercedes-Benz Light Truck Center
immediately. Adjust driving to be
consistent with reduced braking
responsiveness.

445 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
#Battery/Alternator
Stop VehicleThe battery is defective.Stop the vehicle in a safe location or as
soon as it is safe to do so.
Apply the parking brake (page 65).
Do not continue to drive.
Contact an authorized Mercedes-Benz
Light Truck Center.
2Brake WearThe brake pads have reached
their wear limit.Have the brake pads replaced as soon as
possible.
!Brake pad thickness must be visually in-
spected by a qualified technician at the intervals
specified in the Maintenance Booklet.

446 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
;(USA only)
!(Canada only)
Release
Parking BrakeYou are driving with the parking
brake set.Release the parking brake (page 56).
;(USA only)
3(Canada only)
EBV, ABS, ESP Inoperative
See Operator’s ManualThe EBP, the ABS, and the ESP®
have switched off due to a mal-
function. The BAS is also
switched off.
The brake system is still func-
tional but without the EBP, the
ABS, and the ESP
® available.
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.

447 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
;(USA only)
3(Canada only)
Check
Brake Fluid LevelThere is insufficient brake fluid
in the reservoir.Risk of accident! Carefully stop the vehi-
cle in a safe location or as soon as it is
safe to do so.
Apply the parking brake (page 65).
Contact an authorized Mercedes-Benz
Light Truck Center. Do not add brake
fluid! This will not solve the problem.
Warning!G
Driving with the message Check Brake
Fluid Level
displayed can result in an ac-
cident. Have your brake system checked im-
mediately. Do not add brake fluid before
checking the brake system. Overfilling the
brake fluid reservoir can result in spilling
brake fluid on hot engine parts and the
brake fluid catching fire. You could be
seriously burned.
!If you find that the brake fluid in the brake
fluid reservoir has fallen to the minimum mark or
below, have the brake system checked for brake
pad thickness and leaks.

448 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
•Coolant Level
Stop car, switch engine off.The coolant is too hot.
Among other possible causes
(the cooling fan could be
malfunctioning), the poly-V-belt
could be broken.Stop the vehicle in a safe location or
as soon as it is safe to do so.
Turn off the engine.
Apply the parking brake (page 65).
Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise
the engine will overheat due to an
inoperative water pump which may
result in damage to the engine.
Contact an authorized
Mercedes-Benz Light Truck Center.
If it is intact:
Wait for the message to disappear
before restarting the engine.
Doing otherwise could result in seri-
ous engine damage that is not
covered by the Mercedes-Benz
Limited Warranty.
(Continued on next page)

449 Practical hints
What to do if …
During severe operation conditions and
stop-and-go city traffic, the coolant tem-
perature may rise close to 248°F (120°C).
Display symbolDisplay messagePossible cause/consequencePossible solution
Observe the coolant temperature in the
multifunction display (
page 164).
If the temperature rises again:
Contact an authorized
Mercedes-Benz Light Truck Center
immediately.
Warning!G

Driving when your engine is overheated
can cause some fluids which may have
leaked into the engine compartment to
catch fire. You could be seriously
burned.

Steam from an overheated engine can
cause serious burns and can occur just
by opening the engine hood. Stay away
from the engine if you see or hear steam
coming from it.
Turn off the engine, get out of the vehicle
and do not stand near the vehicle until the
engine has cooled down.
!The engine should not be operated with the
coolant temperature above 248°F (120°C).
Doing so may cause serious damage which is
not covered by the Mercedes-Benz Limited
Warranty.