Page 119 of 569

118 Controls in detail
Locking and unlocking
Checking the batteries in the SmartKey 
or SmartKey with KEYLESS-GO*
Press button‹orŒ.
The battery check lamp (
page 110) 
or (
page 113) comes on briefly to in-
dicate that the SmartKey or SmartKey 
with KEYLESS-GO batteries are in 
order.Loss of the SmartKey or SmartKey with 
KEYLESS-GO*
If you lose your SmartKey or SmartKey 
with KEYLESS-GO or mechanical key, you 
should do the following:
Have the SmartKey or SmartKey with 
KEYLESS-GO deactivated by an 
authorized Mercedes-Benz Light 
Truck Center.
Report the loss of the SmartKey or 
SmartKey with KEYLESS-GO or the 
mechanical key to your car insurance 
company immediately.
Have the mechanical lock replaced if 
necessary.
Any authorized Mercedes-Benz Light Truck 
Center will be glad to supply you with a 
replacement.
Opening the doors from the inside
You can open a locked door from the in-
side. Open door only when conditions are 
safe to do so.
1Locking knob
2Inside door handle
iIf the battery check lamp does not come on 
briefly during check, the SmartKey or SmartKey 
with KEYLESS-GO batteries are discharged.
Replace the batteries (
page 479).
You can obtain the required batteries at any 
authorized Mercedes-Benz Light Truck Center.
iIf the batteries are checked within signal 
range of the vehicle, pressing the‹orŒ 
button will lock or unlock the vehicle 
accordingly. 
     
        
        Page 480 of 569

479 Practical hints
Replacing SmartKey batteries
Replacing SmartKey batteries
If the batteries in the SmartKey or the 
SmartKey with KEYLESS-GO* are 
discharged, the vehicle can no longer be 
locked or unlocked. It is recommended to 
have the batteries replaced at an autho-
rized Mercedes-Benz Light Truck Center.
Batteries contain materials that can harm 
the environment if disposed of improperly. 
Recycling of batteries is the preferred 
method of disposal. Many states require 
sellers of batteries to accept old batteries 
for recycling.Replacement batteries: Lithium, type 
CR 2025 or equivalent.
Remove the mechanical key from the 
SmartKey (
page 474).
1Mechanical key
2Battery compartment
Insert mechanical key 1 into opening.
Press mechanical key 1 in direction of 
arrow.
The battery compartment is unlatched.
Pull battery compartment 2 out of the 
SmartKey housing.
3Batteries
4Contact springs
Pull out batteries3.
Using a line-free cloth, insert new bat-
teries 3 under contact springs 4 with 
the positive terminal (+) side facing up.
Return battery compartment 2 into 
housing until it locks into place.
Slide mechanical key 1 back into 
SmartKey.
Check the operation of the SmartKey 
or SmartKey with KEYLESS-GO*.
Warning!G
Keep the batteries out of reach of children.
If a battery is swallowed, seek medical help 
immediately.
iWhen inserting batteries, make sure they 
are clean and free of lint.
iWhen replacing batteries, always replace 
both batteries. The required replacement 
batteries are available at any Mercedes-Benz 
Light Truck Center. 
     
        
        Page 505 of 569

504 Practical hints
Battery
!The battery is a valve-regulated lead acid 
(VRLA) battery, also referred to as “fleece” 
battery. Such batteries do not require topping-up 
of the electrolyte level. VRLA batteries therefore 
do not have cell caps and the battery cover is 
non-removable. Do not attempt to open the 
battery as otherwise the battery will be dam-
aged.
Even though VRLA batteries do not require 
topping-up of the electrolyte level and cannot be 
opened to check the electrolyte level, the 
battery condition must be checked periodically 
by performing a battery conductance test. Refer 
to Maintenance Booklet for battery condition 
testing intervals.
As with any other battery, the battery may 
discharge if the vehicle is not operated for an 
extended period of time. You can connect a 
battery maintenance charge unit tested and 
approved for use on your vehicle model or dis-
connected the battery to prevent battery dis-
charge. Contact an authorized Mercedes-Benz 
Light Truck Center for more information.!The factory-equipped VRLA battery is 
leak-proofed. Only use a battery as replacement 
that has the same security features and is of 
identical size, voltage, and capacity as the 
factory-equipped battery.
The battery, the battery ventilation and the later-
al plug must always be securely installed when 
the vehicle is in operation.
Warning!G
Jump starting must only be done using the 
jump-start contacts located in the engine 
compartment (
page 511).
Warning!G
Failure to follow these instructions can re-
sult in severe injury or death.
Observe all safety instructions and precau-
tions when handling automotive batteries 
(
page 503).
Never lean over batteries while connecting, 
you might get injured.
Battery fluid contains sulfuric acid. Do not 
allow this fluid to come in contact with eyes, 
skin or clothing. In case it does, immediately 
flush affected area with water and seek 
medical help if necessary.
A battery will also produce hydrogen gas, 
which is flammable and explosive. Keep 
flames or sparks away from battery, avoid 
improper connection of jumper cables, 
smoking etc.