2017 MERCEDES-BENZ B-Class key battery

Locking and unlocking
You can start, lock or unlock the vehicle using
KEYLESS-GO. To do this, you only need carry the
SmartKey with you. You can combine the func-
tions of KEYLESS-GO with those of a conven-
tional SmartKey. Unlock the vehicle by using
KEYLESS-GO, for instance, and lock it using the 0037 button on the SmartKey.
The driver's door and the door at which the han-
dle is used, must both be closed. The SmartKey
must be outside the vehicle. When locking or
unlocking with KEYLESS-GO, the distance
between the SmartKey and the corresponding
door handle must not be greater than 3 ft (1 m).
A check which periodically establishes a radio
connection between the vehicle and the Smart-
Key determines whether a valid SmartKey is in
the vehicle. This occurs, for example:
R when starting the drive system
R while driving
R when the external door handles are touched
R during convenience closing X
To unlock the vehicle: touch the inner sur-
face of the door handle.
X To lock the vehicle: touch sensor surface 0043
or 0044.
Make sure that you do not touch the inner
surface of the door handle.
X Convenience closing feature: touch
recessed sensor surface 0044for an extended
period.
Further information on the convenience clos-
ing feature (Y page 77). X
To unlock the tailgate: pull tailgate han-
dle 0043.
Deactivating and activating If you do not intend to use the vehicle for a lon-
ger period of time, you can deactivate KEYLESS-
GO. The SmartKey will then use very little power, thereby conserving battery power. For the pur-
poses of activation/deactivation, the vehicle
must not be nearby.
X To deactivate: press the0037button on the
SmartKey twice in rapid succession.
The battery check lamp of the SmartKey
flashes twice briefly and lights up once, then
KEYLESS-GO is deactivated (Y page 69).
X To activate: press any button on the Smart-
Key.
or X Insert the SmartKey into the ignition lock.
KEYLESS-GO and all of its associated features
are available again. Changing the settings of the locking
system
You can change the settings of the locking sys-
tem. This means that only the driver's door and
the charge socket flap are unlocked when the
vehicle is unlocked. This is useful if you fre-
quently travel on your own.
X To change the setting: press and hold the
0036 and0037 buttons simultaneously for SmartKey
67Opening and closing Z

approximately six seconds until the battery
check lamp flashes twice (Y page 69).
If the setting of the locking system is changed
within the signal range of the vehicle, pressing
the 0037 or0036 button:
R locks or
R unlocks the vehicle
The SmartKey now functions as follows:
X To unlock: press the0036button once.
X To unlock centrally: press the0036button
twice.
X To lock centrally: press the0037button.
The KEYLESS-GO function is changed as fol-
lows: X To unlock the driver's door: touch the inner
surface of the door handle on the driver's
door.
X To unlock centrally: touch the inner surface
of the door handle on the front-passenger
door or the rear door.
X To lock centrally: touch the outer sensor
surface on one of the door handles.
X To restore the factory settings: press and
hold the 0036and0037 buttons simultane-
ously for approximately six seconds until the
battery check lamp flashes twice
(Y page 69). Mechanical key
General notes If the vehicle can no longer be locked or
unlocked with the SmartKey or KEYLESS-GO,
use the mechanical key.
If you use the mechanical key to unlock and
open the driver's door or the trunk lid, the anti-
theft alarm system will be triggered (Y page 65).
There are several ways to turn off the alarm:
X To deactivate the alarm with the key: press
the 0036 or0037 button on the key.
or X Insert the SmartKey into the ignition lock.
or X To deactivate the alarm with KEYLESS-GO:
press the Start/Stop button in the ignition
lock. The SmartKey must be in the vehicle. or
X Lock or unlock the vehicle using KEYLESS-
GO. The SmartKey must be outside the vehi-
cle.
If you unlock the vehicle using the mechanical
key, the charge socket flap will not be unlocked automatically.
X To unlock the charge socket flap: insert the
SmartKey into the ignition lock.
Removing the mechanical key X
Push release catch 0043in the direction of the
arrow and at the same time remove mechan- ical key 0044from the SmartKey.
For further information about:
R Unlocking the driver's door (Y page 73)
R Unlocking the cargo compartment
(Y page 75)
R Locking the vehicle (Y page 73)
Inserting the mechanical key X
Push mechanical key 0044completely into the
SmartKey until it engages and release
catch 0043is back in its basic position. SmartKey battery
Important safety notes G
WARNING
Batteries contain toxic and corrosive substan- ces. If batteries are swallowed, it can result in
severe health problems. There is a risk of fatal injury. 68
SmartKeyOpening and closing

Keep batteries out of the reach of children. If
a battery is swallowed, seek medical attention
immediately.
The SmartKey batteries contain perchlorate
material, which may require special handling
and regard for the environment. National guide- lines must be observed during disposal. In Cal-
ifornia, see www.dtsc.ca.gov/
HazardousWaste/Perchlorate/index.cfm .
Mercedes-Benz recommends that you have the
battery replaced at a qualified specialist work-
shop.
Checking the battery X
Press the 0037or0036 button.
The battery is working properly if battery
check lamp 0043lights up briefly.
The battery is discharged if battery check
lamp 0043does not light up briefly.
X Change the battery (Y page 69).
i If the SmartKey battery is checked within
the signal reception range of the vehicle,
pressing the 0037or0036 button:
R locks or
R unlocks the vehicle
i You can get a battery at any qualified spe-
cialist workshop.
Replacing the battery You require a CR 2025 3 V cell battery. X
Take the mechanical key out of the SmartKey
(Y page 68). X
Press mechanical key 0044into the opening in
the SmartKey in the direction of the arrow
until battery tray cover 0043opens. When doing
so, do not hold cover 0043shut.
X Remove battery tray cover 0043. X
Repeatedly tap the SmartKey against your
palm until battery 0087falls out.
X Insert the new battery with the positive ter-
minal facing upwards. Use a lint-free cloth to
do so.
X Make sure that the surface of the battery is
free of lint, grease and other contaminants.
X Insert the front tabs of battery tray cover 0043
and then press to close it.
X Insert mechanical key into the SmartKey
(Y page 68).
X Check the function of all SmartKey buttons on
the vehicle. SmartKey
69Opening and closing Z

Problems with the SmartKey
Problem
Possible causes/consequences and
0050
0050Solutions You cannot lock or
unlock the vehicle using
the SmartKey. The SmartKey battery is discharged or nearly discharged.
X Vehicles without KEYLESS-GO: try again to lock or unlock the
vehicle using the remote control function of the SmartKey. Point the tip of the SmartKey at the driver's door handle from close range and
press the 0036or0037 button.
X Check the SmartKey battery (Y page 69) and replace it if necessary
(Y page 69).
If this does not work: X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key. There is interference from a powerful source of radio waves.
X Vehicles without KEYLESS-GO: try again to lock or unlock the
vehicle using the remote control function of the SmartKey. Point the
tip of the SmartKey at the driver's door handle from close range and press the 0036or0037 button.
If this does not work: X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key. The SmartKey is faulty.
X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key.
X Have the SmartKey checked at a qualified specialist workshop. You can no longer lock or
unlock the vehicle using
KEYLESS-GO. The SmartKey battery is discharged or nearly discharged.
X Check the SmartKey battery (Y page 69) and replace it if necessary
(Y page 69).
If this does not work: X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key. There is interference from a powerful source of radio waves.
X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key. 70
SmartKeyOpening and closing

Problem
Possible causes/consequences and
0050
0050Solutions KEYLESS-GO is malfunctioning.
X Lock/unlock the vehicle using the remote control function of the
SmartKey.
X Have the vehicle and SmartKey checked at a qualified specialist
workshop.
If the vehicle can also not be locked/unlocked using the remote con-
trol function:
X Unlock (Y page 73) or lock (Y page 73) the vehicle using the
mechanical key.
X Have the vehicle and SmartKey checked at a qualified specialist
workshop. The drive system cannot
be started using the
SmartKey. The on-board voltage is too low.
X Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the drive system again.
If this does not work:
X Check the 12 V battery and charge it if necessary (Y page 248).
or
X Check the high-voltage battery and charge it if necessary
(Y page 118).
or
X Jump-start the vehicle (Y page 249).
or
X Consult a qualified specialist workshop. The drive system cannot
be started using the
Start/Stop button. The
SmartKey is in the vehi-
cle. The vehicle is locked.
X Unlock the vehicle and try to start the vehicle again. The SmartKey battery is discharged or nearly discharged.
X Check the SmartKey battery (Y page 69) and replace it if necessary
(Y page 69).
If this does not work: X Start your vehicle with the SmartKey in the ignition lock. There is interference from a powerful source of radio waves.
X Start your vehicle with the SmartKey in the ignition lock. You have lost a Smart-
Key. X
Have the SmartKey deactivated at a qualified specialist workshop.
X Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. You have lost the
mechanical key. X
Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. SmartKey
71Opening and closing Z

0043
Raises the backrest contour
0044 Softens the backrest contour
0087 Lowers the backrest contour
0085 Hardens the backrest contour Switching the seat heating on/off
Switching on/off G
WARNING
Repeatedly switching on the seat heating can
cause the seat cushion and backrest pads to
become very hot. The health of persons with
limited temperature sensitivity or a limited
ability to react to excessively high tempera-
tures may be affected or they may even suffer burn-like injuries. There is a risk of injury.
Therefore, do not switch the seat heating on
repeatedly. The three red indicator lamps in the button indi-
cate the heating level you have selected.
The system automatically switches down from
level 3to level 2after approximately eight
minutes.
The system automatically switches down from
level 2to level 1after approximately ten
minutes.
The system automatically switches off approx-
imately 20 minutes after it is set to level 1.
X Turn the SmartKey to position 1or 2in the
ignition lock (Y page 109).
X To switch on: press button0043repeatedly
until the desired heating level is set.
X To switch off: press button0043repeatedly
until all the indicator lamps go out.
i If the battery voltage is too low, the seat
heating may switch off.
Problems with the seat heating Problem
Possible causes/consequences and
0050 0050Solutions The seat heating has
switched off prematurely
or cannot be switched
on. The on-board voltage is too low because too many electrical consum-
ers are switched on.
X Switch off electrical consumers that you do not need, such as the
rear window defroster or interior lighting.
Once the battery is sufficiently charged, the seat heating will switch
back on automatically. 82
SeatsSeats
, steering wheel and mirrors

X
To switch on the low-beam headlamps:
turn the SmartKey in the ignition lock to posi-
tion 2or start the drive system.
X Turn the light switch to 0058.
The green 0058indicator lamp in the instru-
ment cluster lights up.
Rear fog lamp
The rear fog lamp improves visibility of your
vehicle for the traffic behind in the event of thick fog. Please take note of the country-specific
regulations for the use of rear fog lamps.
X To switch on the rear fog lamp: turn the
SmartKey in the ignition lock to position 2or
start the drive system.
X Turn the light switch to 0058or0058.
X Press the 005Ebutton.
The yellow 005Eindicator lamp in the instru-
ment cluster lights up.
X To switch off the rear fog lamp: press the
005E button.
The yellow 005Eindicator lamp in the instru-
ment cluster goes out.
Parking lamps ! If the battery charge level is very low, the
parking lamps or standing lamps are switched off automatically in order to preserve energy
to start the drive system. Always park your
vehicle safely and sufficiently lit according to
legal standards. Avoid using the parking
lamps 0060for periods of several hours.
Where possible, switch the right-hand 0064
or left-hand 0063standing lamp on.
X To switch on: turn the light switch to 0060.
The green 0060indicator lamp in the instru-
ment cluster lights up.
Standing lamps
Switching on the standing lamps ensures the
corresponding side of the vehicle is illuminated. X To switch on the standing lamps: the
SmartKey should not be in the ignition lock or it should be in position 0.
X Turn the light switch to 0063(left-hand side of
the vehicle) or 0064(right-hand side of the
vehicle). Combination switch
X
To indicate briefly: press the combination
switch briefly to the pressure point in the
direction of arrow 0044or0085.
The corresponding turn signal flashes three
times.
X To indicate: press the combination switch
beyond the pressure point in the direction of
arrow 0044or0085.
X To switch on the high-beam headlamps:
turn the light switch to 0058or0058.
X Press the combination switch beyond the
pressure point in the direction of arrow 0043.
The high-beam headlamps only switch on in
the 0058 position if the low-beam headlamps
are on.
The blue 0057indicator lamp in the instru-
ment cluster lights up when the high-beam
headlamps are switched on.
X To switch off the high-beam head-
lamps:move the combination switch back to
its normal position.
The blue
0057indicator lamp in the instru-
ment cluster goes out.
X To switch on the high-beam flasher: pull
the combination switch in the direction of
arrow 0087. 88
Exterior lightingLights and
windshield wipers

Control panel in the grab handle in the
rear compartment 0043
To switch the reading lamp on/off Interior lighting control
General notes In order to prevent the vehicle's battery from
discharging, the interior lighting functions are
automatically deactivated after some time
except when the SmartKey is in position 2in the
ignition lock.
The color and brightness for the ambient lighting
may be set via the multimedia system; see the
separate operating instructions.
Automatic interior lighting control X
To switch on: set the switch to center posi-
tion 0084.
X To switch off: set the switch to the 0033
position.
The interior lighting automatically switches on if you:
R unlock the vehicle
R open a door
R remove the SmartKey from the ignition lock
The interior light is activated for a short while
when the SmartKey is removed from the ignition
lock. This delayed switch-off can be adjusted via
the multimedia system; see the separate oper-
ating instructions. Replacing bulbs
Important safety notes
Xenon bulbs: G
DANGER
Xenon bulbs carry a high voltage. You can get an electric shock if you remove the cover of
the Xenon bulb and touch the electrical con-
tacts. There is a risk of fatal injury.
Never touch the parts or the electrical con-
tacts of the Xenon bulb. Always have work on
the Xenon bulbs carried out at a qualified spe-
cialist workshop.
If your vehicle is equipped with Xenon bulbs, you
can recognize this by the following: the cone of light from the Xenon bulbs moves from the top
to the bottom and back again when you start the
drive system. For this to be observed, the lights must be switched on before the drive system is
started.
Headlamps and lights are an important aspect of
vehicle safety. You must therefore make sure
that these function correctly at all times. Have
the headlamp setting checked regularly.
Other bulbs: G
WARNING
Bulbs, lamps and connectors can get very hot when operating. If you change a bulb, you
could burn yourself on these components.
There is a risk of injury.
Allow these components to cool down before changing a bulb.
Do not use a bulb if it has been dropped or if its glass tube has been scratched.
The bulb may explode if
R you touch it
R it is hot
R you drop it
R you scratch it
Use bulbs only in closed lamps that have been
designed for this purpose. Only install spare
bulbs of the same type and the specified volt-
age.
Marks on the glass tube reduce the service life
of the bulbs. Do not touch the glass tube with
your bare hands. If necessary, clean the glass 90
Replacing bulbsLights and windshield wipers