336 Controls in detail
Starter switch positions
SmartKey
Starter switch
0For removing SmartKey
1Power supply for some electrical con-
sumers, such as seat adjustment
2Ignition (power supply for all electrical
consumers) and driving position.
All lamps (except high beam headlamp
indicator lamp and turn signal indicator
lamps unless activated) in the instru-
ment cluster come on. If a lamp in the
instrument cluster fails to come on
when the ignition is switched on, have
it checked and replaced if necessary.
If a lamp in the instrument cluster re-
mains on after starting the engine or
comes on while driving, refer to “Lamps
in instrument cluster” (
page 566).
3Starting position
For information on starting the engine us-
ing the SmartKey, see “Starting with the
SmartKey” (
page 379).
Warning!G
When leaving the vehicle, always remove the
SmartKey or SmartKey with KEYLESS-GO*
from the starter switch, take it with you, and
lock the vehicle. Do not leave children unat-
tended in the vehicle, or with access to an
unlocked vehicle. A child’s unsupervised ac-
cess to a vehicle could result in an accident
and/or serious personal injury.
iWhen you switch on the ignition, the indica-
tor and warning lamps (except high beam head-
lamp indicator lamp and turn signal indicator
lamps unless activated) in the instrument cluster
come on. The indicator and warning lamps (ex-
cept high beam headlamp indicator lamp and
turn signal indicator lamps if activated) should go
out when the engine is running. This indicates
that the respective systems are operational.
!If you turn off the engine using the
SmartKey and
remove the SmartKey from the starter
switch
or
open a door
the transmission will shift to park positionP
automatically.
Keep in mind that turning off the engine with the
SmartKey alone only will automatically shift the
transmission to neutral positionN.
!If the SmartKey cannot be turned in the
starter switch, the battery may not be sufficient-
ly charged.
Check the battery and charge it if necessary
(
page 655).
Get a jump start (page 660).
To prevent accelerated battery discharge or a
completely discharged battery, always remove
the SmartKey from the starter switch when the
engine is not in operation.
458 Controls in detail
Automatic climate control
Maximum cooling MAXCOOL (USA only)
If U is selected on both the left and
right side and there is a high demand for
cooling, the display “MAXCOOL” appears
in the COMAND display.
This provides the fastest possible cooling
of the vehicle interior (when windows and
tilt/sliding sunroof are closed).
Air recirculation mode
Switch to air recirculation mode to prevent
unpleasant odors from entering the vehicle
from the outside (e.g. before driving in a
tunnel). This setting cuts off the intake of
outside air and recirculates the air in the
passenger compartment.
Activating: Press button,
(
page 453) up or down.
The indicator lamp on the button
comes on.Warning!G
Any accumulation of snow and ice should be
removed from the rear window before driv-
ing. Visibility could otherwise be impaired,
endangering you and others.
iIf the rear window defroster switches off too
soon and the indicator lamp goes out, this indi-
cates that too many electrical consumers are op-
erating simultaneously and the load on the
battery is reducing available voltage. The system
responds automatically by deactivating the rear
window defroster.
iMaximum cooling MAXCOOL is only avail-
able when the engine is running.
Warning!G
Fogged windows impair visibility, endanger-
ing you and others. If the windows begin to
fog on the inside, switching off the air
recirculation mode immediately should clear
interior window fogging. If interior window
fogging persists, make sure the air
conditioning (
page 247) is activated, or
press button;.
iThe air recirculation mode is activated auto-
matically at high outside temperatures.
The indicator lamp on button, is not lit when
the air recirculation mode is automatically acti-
vated.
A quantity of outside air is added when the cool-
ing demand is not at maximum.
If the air conditioning has been turned off
(
page 247) or the outside temperature is be-
low 41°F (5°C), the air recirculation mode will
not switch on automatically.
655 Practical hints
Batteries
Batteries
Your vehicle is equipped with two batter-
ies:
The starter battery, located in the en-
gine compartment
The battery for electrical consumers
(consumer battery), located in the
trunk
The batteries should always be sufficiently
charged in order to achieve its rated ser-
vice life. Refer to Maintenance Booklet for
battery maintenance intervals.
If you use your vehicle mostly for short-dis-
tance trips, you will need to have the bat-
tery charge checked more frequently.
When replacing the batteries, always use
batteries approved by Mercedes-Benz.
If you do not intend to operate your vehicle
for an extended period of time, consult an
authorized Mercedes-Benz Center about
steps you need to observe.Batteries contain materials that can harm
the environment if disposed of improperly.
Large 12-volt storage batteries contain
lead. Recycling of batteries is the preferred
method of disposal. Many states require
sellers of batteries to accept old batteries
for recycling.
!Do not tow-start the vehicle.
Warning!G
Observe all safety instructions and precau-
tions when handling automotive batteries.
Risk of explosion.
Fire, open flames and smoking
are prohibited when handling
batteries. Avoid creating sparks.
Battery acid is caustic. Do not
allow it to come into contact
with skin, eyes or clothing.
Wear suitable protective cloth-
ing, especially gloves, apron and
faceguard.
Wear eye protection.
Rinse any acid spills immediate-
ly with clear water. Contact a
physician if necessary.
Keep children away.
Follow the instructions in this
Operator’s Manual.
656 Practical hints
Batteries
!The consumer battery located in the trunk is
a v
alve-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 consumer battery as other-
wise the battery will be damaged.
Even though VRLA batteries do not require top-
ping-up of the electrolyte level and cannot be
opened to check the electrolyte level, the bat-
tery condition must be checked periodically by
performing a battery conductance test. Refer to
Maintenance Booklet for battery condition test-
ing intervals.
As with any other battery, disconnect the con-
sumer battery if you do not intend to operate
your vehicle for an extended period of time to
prevent battery discharge or connect an acces-
sory battery charge unit expressly approved by
Mercedes-Benz for your vehicle model to main-
tain the battery charge. Contact an authorized
Mercedes-Benz Center for further 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 facto-
ry-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
Failure to follow these instructions can re-
sult in severe injury or death.
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.
Warning!G
Do not place metal objects on the battery as
this could result in a short circuit.
Use leak-proof battery only to avoid the risk
of acid burns in the event of an accident.
Take care that you do not become statically
charged, e.g. by wearing synthetic clothing
or rubbing against textiles. For this reason,
you also should not pull or push the battery
over carpets or other synthetic materials.
Never touch the battery first. First touch the
outside body of the vehicle in order to re-
lease any possible electrostatic charges.
657 Practical hints
Batteries
Starter battery (example illustration from
CL 550)
1Negative terminal
2Positive terminal
Disconnecting starter battery
Secure vehicle in place with electronic
parking brake (
page 384).
Shift the automatic transmission toP
(
page 389).
Do not rub the battery with rags or cloths.
The battery could explode if touched due to
electrostatic charge or due to spark forma-
tion.
!Switch off the engine and switch off the ve-
hicle’s internal electrical functions (
page 658)
before you disconnect or remove the battery’s
terminal clamps. You could otherwise destroy
electronic assemblies such as the generator.
Have the battery checked regularly by an autho-
rized Mercedes-Benz Center. Refer to Mainte-
nance Booklet for maintenance intervals or
contact an authorized Mercedes-Benz Center for
further information.
!Do not connect any consumers directly to
the starter battery. The starter battery will other-
wise be discharged.
iOnly replace a discharged battery with a bat-
tery recommended by Mercedes-Benz. The con-
sumer battery is installed in the trunk in such a
way that it is safeguarded as much as possible
against mechanical destruction in the event of
an accident.
iRemove SmartKey from starter switch (vehi-
cles with KEYLESS-GO*: Make sure the vehicle’s
on-board electronics have status 0)
(
page 336) when you turn off the engine and
no longer require any electrical consumers. The
vehicle then uses very little power and the con-
sumer battery is spared.
iIf the consumer battery is discharged, you
must use the mechanical key to unlock the vehi-
cle (
page 635). Since the vehicle has a sepa-
rate starter battery, however, you can still start
the vehicle.
!Always disconnect the starter battery in the
order described below. You could otherwise
damage the vehicle’s electronics.
!Switch off the vehicle’s internal electrical
functions before disconnecting the starter bat-
tery. If the vehicle is stationary for more than one
hour with the SmartKey removed, you do not
need to switch off the vehicle’s internal electrical
functions.
658 Practical hints
Batteries
Switching off vehicle’s internal
electrical functions
Turn off all electrical consumers.
Turn SmartKey in starter switch to po-
sition 0.
Turn SmartKey in starter switch to po-
sition 1.
Wait for 30 seconds.
The vehicle’s internal electrical func-
tions are switched off.
Turn SmartKey in starter switch to po-
sition 0.Disconnecting starter battery
Open the hood (page 512).
Use a 10-mm open-end wrench to dis-
connect the battery negative lead.
Remove cover2 (page 657) from
the positive terminal.
Disconnect the battery positive lead.
Removing starter battery
Pull out the battery ventilation hose
from the battery (depending on battery
arrangement in your vehicle model, the
ventilation hose is located either on the
left or right side of the battery).
Fold bar on starter battery up.
Take out the starter battery.
Charging battery
iVehicles with KEYLESS-GO: remove the
KEYLESS-GO button (
page 337) and use the
SmartKey with KEYLESS-GO like a normal
SmartKey.
!Do not remove the SmartKey!
iFor your convenience, have the starter bat-
tery removed by a Mercedes-Benz Center.
Warning!G
Never charge a battery while still installed in
the vehicle unless the accessory battery
charge unit approved by Mercedes-Benz is
being used. Gases may escape during charg-
ing and cause explosions that may result in
paint damage, corrosion or personal injury.
An accessory battery charge unit specially
adapted for Mercedes-Benz vehicles and
tested and approved by Mercedes-Benz is
available, permitting the charging of the bat-
tery in its installed position. Contact an au-
thorized Mercedes-Benz Center for
information and availability. Charge battery
in accordance with the separate instruc-
tions for the accessory battery charger.
iHave the batteries charged by a
Mercedes-Benz Center. If you charge the batter-
ies yourself, follow the operating instructions for
your charging device.
659 Practical hints
Batteries
Starter battery
Connect the switched-off charging de-
vice to the terminals of the starter bat-
tery. Observe the operating
instructions in the manual for the
charging device while doing so.
Reinstalling starter battery
Install starter battery in engine com-
partment.
Swing retaining bar down.
Reconnecting starter battery
Make sure that the consumer battery in
the trunk is correctly installed and con-
nected.
Turn SmartKey in starter switch to po-
sition 0 and remove.
Connect the positive lead and fasten its
cover2 (
page 657).
Connect negative lead1
(
page 657).
Attach ventilation tube.
Switch on the ignition (page 336).
Start the engine (page 378).
Check vehicle functions.
!Only use charging devices with a maximum
charging voltage of 14.8 V.
Warning!G
During the charge procedure, there is a risk
of acid burns due to gases escaping from
the battery. Do not bend over the battery
during the charge procedure.
!The battery and the battery ventilation hose
must always be securely installed when the vehi-
cle is in operation.
!Always connect the starter battery in the or-
der described below. Otherwise, the vehicle’s
electronics could be damaged.
Warning!G
Do not drive without a properly installed and
connected consumer battery.
Have any work on the consumer battery car-
ried out by an authorized Mercedes-Benz
Center.
!Never invert the terminal connections.
!Make sure that the battery has a plug where
the ventilation tube is attached to it.
661 Practical hints
Jump starting
Jump starting should only be performed on
the starter battery. The starter battery is
located in the engine compartment on the
passenger side (
page 657).
Make sure the two vehicles do not
touch.
Secure vehicle in place with electronic
parking brake (
page 384).
Shift the automatic transmission toP
(
page 389).
Turn off all electrical consumers, ex-
cept hazard warning flashers or work
lights.
Open the hood (page 512).
Start the engine of the vehicle with the
charged battery and run at idle speed.1Negative clamp
2Negative terminal of charged battery
3Positive terminal of charged battery
4Positive terminal of discharged battery
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 655).
iVehicles with KEYLESS-GO: remove the
KEYLESS-GO button (
page 337) and use the
SmartKey with KEYLESS-GO like a normal
SmartKey.