Page 298 of 561

297 Controls in detail
Useful features
The Tele Aid system is available if
it has been activated and is operation-
al. Activation requires a subscription 
for monitoring services, connection 
and cellular air time
vehicle battery power is available
the relevant cellular phone network 
and GPS signals are available and pass 
the information on to the Response 
CenterInitiating an emergency call manually
1Cover
2SOS button
Briefly press on cover1.
The cover opens.
Press SOS button2 briefly.
The indicator lamp in SOS button2 
will flash until the emergency call is 
concluded.
Wait for a voice connection to the 
Response Center.
Close cover1 after the emergency 
call is concluded.
iLocation of the vehicle on a map is only pos-
sible if the vehicle is able to receive signals from 
the GPS satellite network and pass the informa-
tion on to the Response Center.
Warning!G
If the indicator lamp in the SOS button is 
flashing continuously and there was no 
voice connection to the Response Center 
established, then the Tele Aid system could 
not initiate an emergency call (e.g. the rele-
vant cellular phone network is not available). 
The message 
Call Failed appears in the 
multifunction display for approximately 
10 seconds.
Should this occur, assistance must be sum-
moned by other means. 
     
        
        Page 428 of 561

427 Practical hints
What to do if …
Symbol messages
Display symbolDisplay messagePossible cause/consequencePossible solution
ò Replace air filter.The air filter is clogged.Have the air filter checked by an authorized 
Mercedes-Benz Light Truck Center.
#The battery is no longer charging.
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 dis-
tance is increased.
Stop the vehicle in a safe location or as soon as 
it is safe to do so.
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:
Drive immediately to the nearest authorized 
Mercedes-Benz Light Truck Center. Adjust 
driving to be consistent with reduced braking 
responsiveness. 
     
        
        Page 429 of 561
428 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.
{InoperativeDownhill Speed Regulation is 
malfunctioning.Have the Downhill Speed Regulation 
checked by 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.