MERCEDES-BENZ C CLASS 2023 Repair Manual

qSecuring the child restraint system with the
seat belt on the front passenger seat
When installing a belt-secured child restraint sys-
tem on the front passenger seat, always observe the following:sObserve the notes on rearward-facing andforward-facing child restraint systems on thefront passenger seat (  page 58).sObserve the child restraint system manufac-
turer\bs installation and operating instructions.sWhen using a forward-facing child restraint
system in weight category I: remove the head restraint from the respective seat, if possible.
Aser the child restraint system has been
removed, replace the head restraint immedi-
ately and adjust all head restraints correctly.sThe backrest of the forward-facing child
restraint system must, as far as possible, be
resting on the seat backrest of the front passenger seat.sIf the head restraint of the child seat cannot
be fully extended when it is installed in the vehicle; this will result in restrictions on themaximum size setting for child restraint sys-tems in weight category II or III.
Contact with the roof when the headrestraint is fully extended and locked in place
will not result in any restrictions on use.sThe child restraint system must not be put under strain between the roof and the seat
cushion and/or be installed facing in the wrong direction.sThe child restraint system must not be putunder strain by the head restraint. Adjust the head restraints as appropriate.sNever place objects (e.g. cushions) under or
behind the child restraint system.
The seat belt on the front passenger side is equip-
ped with a special seat belt retractor.
When enabled, the special seat belt retractor
ensures that the seat belt does not slacken once
the child seat is secured (  page 53).
&WARNING Risk of injury or death caused
by objects between the seat surface and
the child restraint system
Objects between the seat surface and the
child restraint system could aMect the function
of the automatic co-driver air bag shutoM.
Do not place any objects between the
seat surface and the child restraint sys- tem.Always make sure that the child restraint
system is installed correctly.Set the front passenger seat as far back as possible and move the seat into the highest
position if possible.Fully retract the seat cushion length adjust- ment.Adjust the seat cushion inclination so that thefront edge of the seat cushion is in the highest
position and the rear edge of the seat cushion is in the lowest position.Set the seat backrest to the most verticalposition possible.Occupant safety59

Install the child restraint system.The entire base of the child restraint system must always rest on the sitting surface of thefront passenger seat.Always make sure that the shoulder belt strapis correctly routed from the seat belt outlet of
the vehicle to the shoulder belt guide on the
child restraint system.
The shoulder belt strap must be routed for-
wards and downwards from the seat belt out-
let.If necessary, adjust the seat belt outlet and
the front passenger seat accordingly.Child-proof locks

q Activating or deactivating the child safety lock
for the rear doors
&WARNING Risk of accident and injury due
to children les unattended in the vehicle
If you leave children unattended in the vehicle,
they could, in particular:
= open doors, thereby endangering other
persons or road users.
= get out and be struck by oncoming traPc.
= operate vehicle equipment and become
trapped, for example.
In addition, the children could also set the
vehicle in motion by, for example:
= releasing the parking brake.
= changing the gearbox position.
= starting the vehicle.
Never leave children unattended in the
vehicle.When leaving the vehicle, always take the key with you and lock the vehicle.Keep the key out of reach of children.&WARNING Risk of fatal injury due to expo-
sure to extreme heat or cold in the vehicle
If persons, particularly children, are subjected
to prolonged exposure to intense heat or cold,
there is a risk of severe injury or even death.
Never leave persons, particularly chil-
dren, unattended in the vehicle.&WARNING Risk of accident and injury due
to children les unattended in the vehicle
If children are traveling in the vehicle, they
could, in particular:
= Open doors, thereby endangering other
persons or road users.
= Get out and be struck by oncoming traPc.
= Operate vehicle equipment and become
trapped, for example.
60Occupant safety

Always activate the installed child safety
locks if children are traveling in the vehi-
cle.Never leave children unattended in the vehicle.When leaving the vehicle, always take the SmartKey with you and lock the vehicle.There are child safety locks for the rear doors and
the rear side windows.
The child safety lock on the rear doors secures
each door separately. The doors can no longer be opened from the inside.
Press the lever in direction 1 (activate) or 2
(deactivate).Make sure that the child safety locks are work-
ing properly.
q Activating and deactivating the child safety lock
for the rear side windowsTo activate/deactivate: press button 2.
The rear side window can be opened or closed
in the following cases:
= indicator lamp 1 is lit: via the switch on
the driver\bs doorOccupant safety61

=indicator lamp 1 is oM: via the switch on
the corresponding rear door or driver\bs door
Notes on pets in the vehicle
&WARNING Risk of accident and injury due
to animals les unsecured or unattended in
the vehicle
If you leave animals in the vehicle unattended or unsecured, they could possibly press but-
tons or switches.
An animal may: = Activate vehicle equipment and become
trapped, for example
= Switch systems on or oM and endanger
other road users
Unsecured animals may be thrown around in
the vehicle in the event of an accident or sud-
den steering and braking maneuvers and
injure vehicle occupants in the process.
Never leave animals in the vehicle unat-
tended.Always correctly secure animals while
driving, e.g. using a suitable animal car-
rier.62Occupant safety

SmartKey
Overview of key functions
&WARNING Risk of accident and injury due
to children les unattended in the vehicle
If you leave children unattended in the vehicle,
they could, in particular:
= open doors, thereby endangering other
persons or road users.
= get out and be struck by oncoming traPc.
= operate vehicle equipment and become
trapped, for example.
In addition, the children could also set the
vehicle in motion by, for example:
= releasing the parking brake.
= changing the gearbox position.
= starting the vehicle.
Never leave children unattended in the
vehicle.When leaving the vehicle, always take the key with you and lock the vehicle.Keep the key out of reach of children.*NOTE Damage to the SmartKey caused by
magnetic NeldsKeep the SmartKey away from strong
magnetic Nelds.Vehicle key with panic alarm1Opens/closes the trunk lid2Unlocks (with embossed surface)3Locks4Indicator lamp5Panic alarm\bIf indicator lamp 4 does not light up aser
you press the Ü or U button, the bat-
tery is weak or possibly discharged. Replace
the battery as soon as possible.
Replace the key battery (  page 65).
The key locks and unlocks the following compo-
nents:
= Doors
= Fuel Nller Oap
= Trunk lid
If the vehicle is not opened within approximately 40 seconds aser unlocking, it will lock again. Anti-
thes protection will be armed again.
Do not keep the key together with electronic devi- ces or metal objects. This can aMect the key\bs
functionality.
Opening and closing63

Activating/deactivating the acoustic locking veriN-
cation signal
Multimedia system:
4 © 5
Settings 5
Vehicle
5 Open/Close
Activate or deactivate the Acoustic Lock.
Activating/deactivating the panic alarm
Requirements:
= The vehicle is switched oM.
To activate: press button 1 for approximately
one second.
A visual and audible alarm is triggered.To deactivate: brieOy press button 1 again.
or
Press the start/stop button.
A SmartKey belonging to the vehicle must be detected in the vehicle.
Changing the unlocking settings
Possible unlocking functions of the SmartKey:
= Central unlocking
= Unlocking the driver\bs door and fuel Nller Oap
To switch between settings: press the Ü
and U buttons simultaneously for approx-
imately six seconds until the indicator lamp
Oashes twice.
Options if the unlocking function for the driver\bs
door and fuel Nller Oap has been selected:
= To unlock the vehicle centrally: press the
Ü button twice.
=
Vehicles with KEYLESS-GO: if you touch the
inner surface of the door handle on the driv- er\bs door, only the driver\bs door and the fuel
Nller Oap are unlocked.
Deactivating the function of the key
Vehicles with KEYLESS-GO: if you deactivate the
function of the key, the KEYLESS-GO functions will also be deactivated. Access or drive authorization
by KEYLESS-GO will then no longer be possible with that particular key. Activate the function of
the key so that all its functions will again be avail- able.
You can also deactivate the function of the key to
reduce the energy consumption of the key if you do not use the vehicle or a key for an extended
period of time.
To deactivate: press and hold the U key
button.64Opening and closing

With the U button pressed, immediately
press the Ü key button twice in quick suc-
cession.
The indicator light on the key will light up once
brieOy and once for a long time.To activate: press any button on the key.\bWhen the vehicle is started with the key in the
stowage compartment of the center console,
the function of the key will be activated auto- matically (  page 151).
Removing/inserting the emergency key
Removing the emergency key
Press release button 1.
Emergency key 2 is pushed out slightly.Fully remove emergency key 2.
Inserting the emergency key
Insert emergency key 2 at marking 3 until
it engages.\bYou can use emergency key 2 to attach the
key to a key ring.Replacing the key battery&DANGER Risk of fatal injuries due to swal-
lowing batteries
Batteries contain toxic and corrosive substan-
ces. If batteries are swallowed or otherwise
enter the body, severe internal burns can
occur within two hours.
There is a risk of fatal injury.
Keep batteries out of the reach of chil-
dren.If the battery compartment cover and/or
lid do not close securely, stop using the key and keep it away from children.If batteries are swallowed or otherwise
enter the body, seek immediate medical
attention.Opening and closing65

+ENVIRONMENTAL NOTE Environmental
damage due to improper disposal of bat-
teries
Batteries contain pollutants. It is
illegal to dispose of them with the household rubbish.

Dispose of batteries in an
environmentally responsible manner.
Take discharged batteries to a qualiNed
specialist workshop or to a collection
point for used batteries.
Requirements: = You require a CR 2032 3 V cell battery.
Mercedes-Benz recommends that you have the
battery replaced at a qualiNed specialist work-
shop.
Remove the mechanical key (  page 65).Press mechanical key 2 into the opening in
the key in the direction of the arrow until
cover 1 opens. When doing so, do not hold
cover 1 closed.Insert mechanical key 2 into the opening
and lis up covering 3 and remove it.Repeatedly tap the key against your palm until
battery 4 falls out of the key.Insert the new battery with the positive pole
facing upwards. Use a lint-free cloth to do so.Make sure that the surface of the battery is
free of lint, grease and other impurities.Insert the front tabs of covering 3 into the
housing and then press on both sides to close it.Make sure that covering 3 is completely
closed.Insert the front tabs of cover 1 into the
housing and then press until it is completely
closed.Insert the mechanical key again (  page 65).66Opening and closing

Problems with the SmartKey, troubleshooting
You can no longer lock or unlock the vehiclePossible causes: = The SmartKey battery is weak or discharged.
Check the battery using the indicator lamp
(  page 63).Replace the SmartKey battery, if necessary
(  page 65).Use the replacement key.Use the emergency key to lock or unlock
(  page 70).Have the SmartKey checked at a qualiNed spe-
cialist workshop.
There is interference from a powerful radio signal
source
Possible causes if the function of the SmartKey is impaired:
= high voltage power lines
= mobile phones
= electronic devices (notebooks, tablets)
=shielding due to metallic objects or induction
loops for electrical gate systems or automatic
barriersMake sure that there is suPcient distance
between the SmartKey and the potential
source of interference.
You have lost a SmartKey.
Have the SmartKey deactivated at a qualiNed
specialist workshop.If necessary, have the mechanical lock
replaced as well.Doors
Unlocking/opening the doors from the inside
To unlock and open a front door: pull door
handle 1.To unlock a rear door: pull the rear door han-
dle.To open a rear door: pull the rear door handle
again.Opening and closing67

Centrally locking and unlocking the vehicle fromthe insideTo unlock: press button 1.To lock: press button 2.
The red indicator lamp on button 2 will light
up once the vehicle is locked.\bThe buttons are also located on the front
passenger and rear doors.This does not lock or unlock the fuel Nller Oap.
The vehicle is not unlocked:
= if you have locked the vehicle using the Smart-
Key
= if you have locked the vehicle using KEYLESS-
GO
Locking/unlocking the vehicle with KEYLESS-GO
Requirements
= The key is outside the vehicle.
= The distance between the key and the vehicle
does not exceed 3 s (1 m).
= The driver\bs door and the door on which the
door handle is used are closed.
*NOTE Damage to the vehicle caused by
unintentionally opening the trunk lid
= When using an automatic car wash
= When using a high pressure cleaner
Deactivate the function of the SmartKey
in these situations.orMake sure that the SmartKey is at a min-
imum distance of 10 s (3 m) away from
the vehicle.
Observe the notes:
= on washing the vehicle in a car wash
(  page 309)
= on using a high pressure cleaner
(  page 311)
68Opening and closing