2019 MERCEDES-BENZ SLC key battery

ProblemPossible causes/consequences andPPSolutions
The engine cannot bestarted using the Smart-Key.
The on-board voltage is too low.
XSwitch off non-essential consumers, e.g. seat heating or interiorlighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary(Ypage 259).
or
XJump-start the vehicle (Ypage 260).
or
XConsult a qualified specialist workshop.
The engine cannot bestarted using KEYLESS-GO. The SmartKey is inthe vehicle.
The vehicle is locked.
XUnlock the vehicle and try to start the vehicle again.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 69) and replace it if neces-sary (Ypage 69).
If this does not work:
XStart your vehicle with the SmartKey in the ignition lock.
There is interference from a powerful source of radio waves.
XStart your vehicle with the SmartKey in the ignition lock.
You have lost a Smart-Key.XHave the SmartKey deactivated at a qualified specialist work-shop.
XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
You have lost themechanical key.XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
The side windows can-not be opened or closedusing the convenienceopening/closing fea-ture.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 69) and replace it if neces-sary (Ypage 69).
Doors
Important safety notes
GWARNING
If children are left unsupervised in the vehi-
cle, they could:
Roperate the vehicle's equipment
Additionally, children could set the vehicle in
motion if, for example, they:
Rrelease the parking brake
Rshift the automatic transmission out of
park position]
Rstart the engine
There is a risk of an accident and injury.
Doors71
Opening and closing
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Never leave children or animals unattended
in the vehicle.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. This
also applies for the Digital Vehicle Key if the
"Digital Vehicle Key" function is activated via
Mercedes me connect.
Unlocking and opening doors from
the inside
!The side windows will not open/close ifthe battery is discharged or if the side win-dows have iced up. It will then not be possi-ble to close the door. Do not attempt toforce the door closed. You could otherwisedamage the door or the side window.
You can open a door from inside the vehicleeven if it has been locked.
If the vehicle has previously been locked fromthe outside, opening a door from the insidewill trigger the anti-theft alarm system. Switchoff the alarm (Ypage 64).
XPull door handleD.If the door is locked, locking knobCpopsup. The door is unlocked and can beopened.
When a door is opened, the side window onthat side opens slightly. When the door isclosed, the side window closes again.
Centrally locking and unlocking the
vehicle from the inside
You can centrally lock or unlock the vehiclefrom the inside. For example, you can unlock
the front-passenger door from the inside orlock the vehicle before you pull away.
XTo unlock:press buttonC.
XTo lock:press buttonD.If the front-passenger door is closed, thevehicle locks.
The central locking button does not lock orunlock the fuel filler flap or the stowage com-partment in the center console.
You cannot unlock the vehicle centrally fromthe inside if the vehicle has been locked withthe SmartKey or KEYLESS-GO.
You can open a door from inside the vehicleeven if it has been locked.
If a locked door is opened from the inside, theprevious unlock status of the vehicle will betaken into consideration if:
Rthe vehicle was locked using the lockingbutton for the central locking, or
Rif the vehicle was locked automatically
The vehicle will be fully unlocked if it had pre-viously been fully unlocked. If only the driver'sdoor had been previously unlocked, only thedoor which has been opened from the inside isunlocked.
72Doors
Opening and closing

XTake the mechanical key out of the Smart-Key (Ypage 68).
XInsert the mechanical key into the trunk lidlock as far as it will go.
XTurn the mechanical key from positionGcounter-clockwise as far as it will go to posi-tionH. Simultaneously pull the trunk lidhandle.The trunk is unlocked.
XTurn the mechanical key back to positionGand remove it.
XInsert the mechanical key into the Smart-Key.
Emergency release for the trunk
You can unlock the trunk lid from the insidewith the emergency release button.
XPress emergency release buttonCbriefly.The trunk lid unlocks and opens.
The trunk lid can be unlocked and opened withthe trunk lid emergency release when the vehi-cle is stationary or while driving.
The trunk lid emergency release does notunlock the trunk lid if the battery is disconnec-ted or discharged.
Trunk lid emergency release light:
REmergency release buttonCflashes for30 minutes after the trunk lid is opened
REmergency release buttonCflashes for60 minutes after the trunk lid is closed
Side windows
Important safety notes
GWARNING
While opening the side windows, body parts
could become trapped between the side
window and the door frame as the side win-
dow moves. There is a risk of injury.
Make sure that nobody touches the side
window during the opening procedure. If
somebody becomes trapped, release the
switch or pull the switch to close the side
window again.
GWARNING
While closing the side windows, body parts
in the closing area could become trapped.
There is a risk of injury.
When closing make sure that no parts of the
body are in the closing area. If somebody
becomes trapped, release the switch or
press the switch to open the side window
again.
GWARNING
If children operate the side windows they
could become trapped, particularly if they
are left unsupervised. There is a risk of
injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle.
Never leave children unsupervised in the
vehicle.
Side window reversing feature
The front side windows are equipped with anautomatic reversing feature. If a solid objectblocks or restricts the upward movement of
Side windows75
Opening and closing
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has been set correctly. If this is not thecase, repeat the steps above.
Problems with the side windows
GWARNING
If you close a side window again immediately after it has been blocked or reset, the side win-
dow closes with increased or maximum force. The reversing feature is then not active. Parts of
the body could be trapped in the closing area in the process. This poses an increased risk of
injury or even fatal injury.
Make sure that no parts of the body are in the closing area. To stop the closing process,
release the switch or push the switch again to reopen the side window.
ProblemPossible causes/consequences andPPSolutions
A side window cannotbe closed because it isblocked by objects, e.g.leaves in the windowguide.
XRemove the objects.
XClose the side window.
A side window cannotbe closed and you can-not see the cause.
If a side window is obstructed during closing and reopens againslightly:
XImmediately after the window blocks, pull the correspondingswitch again until the side window has closed.The side window is closed with increased force.
If a side window is obstructed again during closing and reopensagain slightly:
XImmediately after the window blocks, pull the correspondingswitch again until the side window has closed.The side window is closed without the automatic reversing fea-ture.
The side windows can-not be opened or closedusing the convenienceopening/closing fea-ture.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 69) and replace it if neces-sary (Ypage 69).
Roof
Important safety notes
GWARNING
If you do not fully open/close the soft top,
the soft-top hydraulics depressurize after a
short time. This causes the soft top to lower
unexpectedly and may cause you or others
to be trapped. There is a risk of injury.
Always open or close the soft top com-
pletely.
GWARNING
Closing the roof manually is a complicated
and technically demanding procedure, which
requires a lot of strength. You or others can
become trapped. There is a risk of injury.
78Roof
Opening and closing

Problems with the seat heating
ProblemPossible causes/consequences andPPSolutions
The seat heating hasswitched off prema-turely or cannot beswitched on. The vehi-cle's electrical systemvoltage is too lowbecause too many elec-trical consumers areswitched on.
Switch off electrical consumers that you do not need, such as therear window defroster or interior lighting.
Once the battery is sufficiently charged, switch on the seat heatingagain.
AIRSCARF
Setting head level heating (AIRSCARF)
GWARNING
When AIRSCARF is switched on, very hot air
can flow from the vents in the head
restraints. This could result in burns in the
immediate vicinity of the air vents. There is a
risk of injury.
Reduce the heater output before it becomes
too hot.
The AIRSCARF function warms the head andneck area of vehicle occupants with warm air.The warm air flows out of the holes in the headrestraints.
The three red indicator lamps in the buttonindicate the heating level you have selected.
XEnsure that the SmartKey is in positionHin the ignition lock.
XTo switch on:press buttonC.Three red indicator lamps in the button lightup. The blower starts up after a preheatingphase of seven seconds.
XPress buttonCrepeatedly until the desiredheating level is set.
XTo switch off:press buttonCrepeatedlyuntil all the indicator lamps go out.
iThe blower continues running for sevenseconds to cool down the heating elements.
iIf the battery voltage is too low, AIRSCARFmay switch off.
Problems with AIRSCARF
AIRSCARF has switched off prematurely or willnot switch on. The vehicle's electrical systemvoltage is too low because too many electricalconsumers are switched on.
XSwitch off electrical consumers that you donot need, such as the rear window defrosteror interior lighting.
XSwitch on AIRSCARF again.
Steering wheel
Important safety notes
GWARNING
You could lose control of your vehicle if you
do the following while driving:
Radjust the driver's seat, head restraint,
steering wheel or mirrors
Rfasten the seat belt
There is a risk of an accident.
Steering wheel89
Seats, steering wheel and mirrors
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When the engine is running, the vehicle is sta-tionary and in bright ambient light: if you turnthe light switch to the`position, the day-time running lamps and parking lamps switchon.
If the engine is running and you turn the lightswitch toX, the manual settings take prec-edence over the daytime running lamps.
USA only:
The daytime running lamps improve the visibil-ity of your vehicle during the day. To do this,the daytime running lamps function must beswitched on using the on-board computer(Ypage 176).
If the engine is running and you turn the lightswitch to`orX, the manual settingstake precedence over the daytime runninglamps.
Low-beam headlamps
GWARNING
When the light switch is set toX, the
low-beam headlamps may not be switched
on automatically if there is fog, snow or
other causes of poor visibility due to the
weather conditions such as spray. There is a
risk of an accident.
In such situations, turn the light switch to
X.
Even if the light sensor does not detect that itis dark, the parking lamps and low-beam head-lamps switch on when the ignition is switchedon and the light switch is set to theXposi-tion. This is a particularly useful function in theevent of rain and fog.
XTo switch on the low-beam headlamps:turn the SmartKey to positionHin the igni-tion lock or start the engine.
XTurn the light switch toX.The greenXindicator lamp in the instru-ment cluster lights up.
Rear fog lamp
The rear fog lamp improves visibility of yourvehicle for the traffic behind in the event ofthick fog. Please take note of the country-spe-cific regulations for the use of rear fog lamps.
XTo switch on the rear fog lamp:turn theSmartKey to positionHin the ignition lockor start the engine.
XTurn the light switch toXorX.
XPress the^button.The yellow^indicator lamp in the instru-ment cluster lights up.
XTo switch off the rear fog lamp:press the^button.The yellow^indicator lamp in the instru-ment cluster goes out.
Parking lamps
!If the battery charge is very low, the park-ing lamps or standing lamps are automati-cally switched off to enable the next enginestart. Always park your vehicle safely and ina well lit area, in accordance with the rele-vant legal stipulations. Avoid using the`parking lamps over a period of severalhours. If possible, switch on the right-handdor left-handcstanding lamps.
XTo switch on:turn the light switch to`.The green`indicator lamp in the instru-ment cluster lights up.
Standing lamps
Switching on the standing lamps ensures thecorresponding side of the vehicle is illumina-ted.
XTo switch on the standing lamps:theSmartKey is not in the ignition lock or it is inposition

Problems with the rear window defroster
ProblemPossible causes/consequences andPPSolutions
The indicator lamp onthelbuttonflashes. The rear win-dow defroster has deac-tivated prematurely orcannot be activated.
The on-board voltage is too low because too many electrical con-sumers are switched on.
XSwitch off any consumers that are not required, e.g. readinglamps, interior lighting or the seat heating.When the battery is sufficiently charged, the rear windowdefroster can be activated again.
The roof is open.
XClose the roof.When the roof is closed, the rear window defroster can be activa-ted again.
Switching air-recirculation mode
on/off
General notes
If you switch on air-recirculation mode, thewindows can fog up more quickly, in particularat low temperatures. Only use air-recirculationmode briefly to prevent the windows from fog-ging up.
Activating/deactivating
XTurn the SmartKey to positionHin the igni-tion lock (Ypage 118).
XTo activate:press therbutton.The indicator lamp in therbutton lightsup.
iAir-recirculation mode is automaticallyactivated at high levels of pollution (dual-zone automatic climate control only) or athigh outside temperatures. When air-recir-culation mode is activated automatically,the indicator lamp in therbutton is notlit. Outside air is added after about30 minutes.
XTo deactivate:press therbutton.The indicator lamp in therbutton goesout.
iAir-recirculation mode deactivates auto-matically:
Rafter approximately five minutes at out-side temperatures below approximately41 ‡ (5 †)
Rafter approximately five minutes if coolingwith air dehumidification is deactivated
Rafter approximately 30 minutes at outsidetemperatures above approximately 41 ‡(5 †) if the "Cooling with air dehumidifi-cation" function is activated
Switching the residual heat on or off
General notes
The residual heat function is only available onvehicles for Canada.
It is possible to make use of the residual heatof the engine to continue heating the station-ary vehicle for up to 30 minutes after theengine has been switched off. The heatingtime depends on the set interior temperature.
Activating/deactivating
XTurn the SmartKey to position

Battery acid is caustic. Avoid con-tact with skin, eyes or clothing.
Wear suitable protective clothing,especially gloves, apron and face-guard.
Rinse any acid spills immediatelywith clear water. Contact a physi-cian if necessary.
Wear eye protection.
Keep children away.
Observe this Operator's Manual.
For safety reasons, Mercedes-Benz recom-mends that you only use batteries which havebeen tested and approved for your vehicle byMercedes-Benz. These batteries provideincreased impact protection to prevent vehicleoccupants from suffering acid burns shouldthe battery be damaged in the event of anaccident.
In order for the battery to achieve the maxi-mum possible service life, it must always besufficiently charged.
Like other batteries, the vehicle battery maydischarge over time if you do not use the vehi-cle. In this case, have the battery disconnec-ted at a qualified specialist workshop. You canalso charge the battery with a charger recom-mended by Mercedes-Benz. Contact a quali-fied specialist workshop for further informa-tion.
Have the battery condition of charge checkedmore frequently if you use the vehicle mainlyfor short trips or if you leave it standing idlefor a lengthy period. Consult a qualified spe-cialist workshop if you wish to leave your vehi-cle parked for a long period of time.
Remove the SmartKey if you park the vehicleand do not require any electrical consumers.The vehicle will then use very little energy,thus conserving battery power.
If the power supply has been interrupted, e.g.if you reconnect the battery, you will have to:
Rreset the function for automatically foldingthe exterior mirrors in/out by folding themirrors out once (Ypage 93)
Rset the clock
On vehicles with a multimedia system, thetime is set automatically.
Charging the battery
GWARNING
During charging and jump-starting, explosive
gases can escape from the battery. There is
a risk of an explosion.
Particularly avoid fire, open flames, creating
sparks and smoking. Ensure there is suffi-
cient ventilation while charging and jump-
starting. Do not lean over a battery.
GWARNING
Battery acid is caustic. There is a risk of
injury.
Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean
over the battery. Keep children away from
batteries. Wash away battery acid immedi-
ately with plenty of clean water and seek
medical attention.
GWARNING
A discharged battery can freeze at tempera-
tures below freezing point. When jump-start-
ing the vehicle or charging the battery,
gases can escape from the battery. There is
a risk of an explosion.
Allow the frozen battery to thaw out before
charging it or jump-starting.
!Only use battery chargers with a maximumcharging voltage of 14.8V.
!Onlycharge the battery using the jump-starting connection point.
The jump-starting connection point is in theengine compartment.
Battery (vehicle)259
Breakdown assistance
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