ECU MERCEDES-BENZ B-CLASS HATCHBACK 2015 Service Manual

The braking performance of the electric motor
using recuperative braking is, in some operating modes, either reduced or not effective:
R when the charge status of the high-voltage
battery increases
R if the high-voltage battery is not yet at a nor-
mal operating temperature
R when driving close to the maximum speed
R when the vehicle is almost stationary
R in transmission position N
R during and after ESP stability control
If you do not make an additional effort to apply
the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative braking effect by applying the
brake yourself.
Downhill gradients On long, steep gradients, you must reduce the
load on the brakes by selecting maximum recu- peration. This prevents the brakes overheating
and causing excessive wear.
Recuperation allows the vehicle to be deceler-
ated without placing a load on the braking sys-
tem.
Do not depress the brake pedal continuously
while the vehicle is in motion, e.g. never cause
the brakes to rub by constantly applying light
pressure to the pedal. This results in excessive
and premature wear to the brake pads.
Heavy and light loads G
WARNING
The braking system can overheat if you leave your foot on the brake pedal while driving.
This increases the braking distance and could
even cause the braking system to fail. There is
a risk of an accident.
Never use the brake pedal as a footrest. Do
not simultaneously depress both the brake
pedal and the accelerator pedal while driving.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If heavy demands are made on the brakes, do
not park the vehicle immediately. Drive on for a
short while. This allows the airflow to cool the
brakes more quickly. If the brakes have been used only moderately,
you should occasionally test their effectiveness.
To do this, brake more firmly from a higher
speed, paying attention to traffic conditions.
This improves the grip of the brakes.
Wet road surfaces If you have driven for a long time in heavy rain
without braking, there may be a delayed reac-
tion from the brakes when braking for the first
time. This may also occur after a car wash or
after driving through deep water.
You will have to depress the brake pedal more
firmly. Maintain a greater distance to the vehicle
in front.
After driving on a wet road or having the vehicle washed, brake firmly while paying attention to
the traffic conditions. This will warm up the
brake discs, thereby drying them more quickly
and protecting them against corrosion.
Limited braking performance on salt-
treated roads If you drive on salt-treated roads, a layer of salt
may form on the brake discs and pads. This can increase the braking distance considerably.
R In order to prevent any salt build-up, apply the
brakes occasionally while paying attention to the traffic conditions.
R Carefully depress the brake pedal at the end
of the journey and when starting the next
journey.
R Maintain a much greater distance to the vehi-
cle in front.
New brake pads/linings Brake pads/linings and discs that are either new
or have been replaced only achieve optimum
braking effect after several hundred kilometres
of driving. Compensate for the reduced braking effect by applying greater force to the brake
pedal.
For safety reasons, Mercedes-Benz recom-
mends that you only have brake pads/linings
fitted to your vehicle which have been approved
for Mercedes-Benz vehicles or which corre-
spond to an equivalent quality standard. Brake
pads/linings which have not been approved for
Mercedes-Benz vehicles or which are not of an
equivalent quality could affect your vehicle's
operating safety. Driving tips
149Driving and parking Z

Driving on wet roads
Aquaplaning If water has accumulated to a certain depth on
the road surface, there is a danger of aquaplan- ing occurring, even if:
R you are driving at low speeds
R the tyres have adequate tread depth
For this reason, drive in the following manner in the event of heavy rain or in conditions in which
aquaplaning can occur:
R lower your speed
R avoid tyre ruts
R avoid sudden steering movements
R brake carefully
Driving on flooded roads !
Bear in mind that vehicles travelling in front
or in the opposite direction create waves. This may cause the maximum permissible water
depth to be exceeded.
These notes must be observed under all cir-
cumstances. You could otherwise damage
the engine, the electronics or the transmis-
sion.
If you must drive on stretches of road on which
water has collected, please bear in mind that:
R in the case of standing water, the water level
must be no higher than the lower edge of the
vehicle body
R you should drive no faster than walking pace Winter driving
G
WARNING
If you increase the recuperation level on slip- pery road surfaces, the drive wheels may lose
their traction. This increases the risk of skid-
ding and having an accident.
Do not increase the recuperation level on slip-
pery road surfaces.
Have your vehicle winterproofed at a qualified
specialist workshop at the onset of winter.
You should drive particularly carefully on slip-
pery road surfaces. Avoid sudden acceleration, steering and braking manoeuvres. Do not use
cruise control.
If the vehicle threatens to skid or cannot be
stopped when moving at low speed:
X Shift the DIRECT SELECT lever to position N.
X Try to bring the vehicle under control by using
corrective steering.
The outside temperature indicator is not
designed to serve as an ice-warning device and
is therefore unsuitable for that purpose.
Changes in the outside temperature are dis-
played after a short delay.
Indicated temperatures just above the freezing
point do not guarantee that the road surface is
free of ice. The road may still be icy, especially in
wooded areas or on bridges.
You should pay special attention to road condi-
tions when temperatures are around freezing
point.
Further information on driving with snow chains (Y page 269).
Further information on driving with summer
tyres (Y page 268).
Observe the notes in the "Winter operation" sec-
tion (Y page 268). Driving systems
Cruise control
General notes Cruise control maintains a constant road speed
for you. It brakes automatically in order to avoid
exceeding the set speed. Change into transmis-
sion position D-
(Y page 132) on long and steep
downhill gradients. This increases recuperation
in overrun mode. This relieves the load on the
brake system and prevents the brakes from
overheating and wearing too quickly.
Use cruise control only if road and traffic con-
ditions are appropriate for maintaining a steady
speed for a prolonged period. You can store any road speed above 30 km/h.
The speed indicated in the speedometer may
differ slightly from the speed stored. 150
Driving syste
msDriving and parking

accelerates or brakes. If you do not know
what the stored speed is, the vehicle may
accelerate or brake unexpectedly. There is a
risk of an accident.
Take the traffic conditions into account
before calling up the stored speed. If you do
not know what the stored speed is, store the
desired speed again.
X Briefly pull the cruise control lever towards
you =.
X Remove your foot from the accelerator pedal.
The first time cruise control is activated, it
stores the current speed or regulates the
speed of the vehicle to the previously stored
speed.
Setting a speed Bear in mind that it may take a brief moment
until the vehicle has accelerated or braked to
the set speed.
X Press the cruise control lever up :for a
higher speed or down ?for a lower speed.
X Keep the cruise control lever pressed until the
desired speed is reached.
X Release the cruise control lever.
The new speed is stored.
X To adjust the set speed in 1 km/h incre-
ments: briefly press the cruise control lever
up : or down ?to the pressure point.
The last stored speed increases or decreases
in 1 km/h increments.
X To adjust the set speed in 10 km/h incre-
ments: briefly press the cruise control lever
up : or down ?beyond the pressure point.
The last stored speed increases or decreases
in 10 km/h increments.
i Cruise control is not deactivated if you
depress the accelerator pedal. For example, if
you accelerate briefly to overtake, cruise con-
trol adjusts the vehicle's speed to the last
speed stored after you have finished overtak-
ing. Deactivating cruise control There are several ways to deactivate cruise con-
trol:
X Briefly press the cruise control lever forwards
B.
or X Brake.
or X Briefly press the cruise control lever in the
direction of arrow A.
Variable SPEEDTRONIC is selected. LIM indi-
cator lamp ;in the cruise control lever lights
up.
Cruise control is automatically deactivated if:
R the vehicle is secured with the electric park-
ing brake
R you are driving at less than 30 km/h
R ESP ®
intervenes or you deactivate ESP ®
R you shift the transmission to position Nwhile
driving
If cruise control is deactivated, you will hear a
warning tone. You will see the Cruise con‐ Cruise con‐
trol off
trol off message in the multifunction display
for approximately five seconds.
i The last speed stored is cleared when you
switch off the engine. SPEEDTRONIC
General notes SPEEDTRONIC brakes automatically so that you
do not exceed the set speed. Change into trans-
mission position D-
(Y page 132) on long and
steep downhill gradients. This increases recu-
peration in overrun mode. This relieves the load on the brake system and prevents the brakes
from overheating and wearing too quickly. If youneed additional braking, depress the brake
pedal repeatedly rather than continuously.
i The speed indicated in the speedometer
may differ slightly from the limit speed stored.
Important safety notes If you fail to adapt your driving style, SPEED-
TRONIC can neither reduce the risk of an acci-
dent nor override the laws of physics. SPEED-
TRONIC cannot take into account road, weather152
Driving systemsDriving and parking

Switching SPEEDTRONIC to passive
If you depress the accelerator pedal beyond the
pressure point (kickdown), SPEEDTRONIC is
switched to passive mode. The following mes-
sage appears in the multifunction display:
SPEEDTRONIC passive SPEEDTRONIC passive.
You can then exceed the stored speed. SPEED-
TRONIC is activated again if you:
R drive slower than the stored speed without
kickdown
R set a new speed or
R call up the last speed stored again
The SPEEDTRONIC passive SPEEDTRONIC passive message in the
multifunction display disappears.
Deactivating variable SPEEDTRONIC
It is not possible to deactivate variable SPEED-
TRONIC by braking.
There are several ways to deactivate variable
SPEEDTRONIC:
X Briefly press the cruise control lever forwards
B.
or X Briefly press the cruise control lever in the
direction of arrow A.
LIM indicator lamp ;in the cruise control
lever goes out. Variable SPEEDTRONIC is
deactivated.
Cruise control is selected.
i The last speed stored is cleared when you
switch off the engine. HOLD function
General notes The HOLD function can assist the driver in the
following situations:
R when pulling away, especially on steep slopes
R when manoeuvring on steep slopes
R when waiting in traffic
The vehicle is kept stationary without the driver having to depress the brake pedal.
The braking effect is cancelled and the HOLD
function is deactivated when you depress the
accelerator pedal to pull away. Important safety notes G
WARNING
When leaving the vehicle, it can still roll away despite being braked by the HOLD function if:
R there is a malfunction in the system or in
the voltage supply
R the HOLD function is deactivated by the
accelerator pedal being depressed, e.g. by
a vehicle occupant
R the electrical system in the engine com-
partment, the battery or the fuses are tam-
pered with
R the battery is disconnected
There is a risk of an accident.
Before leaving the vehicle, always deactivate
the HOLD function and secure the vehicle
from rolling away.
! When the HOLD function is activated, the
vehicle brakes automatically in certain situa-
tions.
To avoid damage to the vehicle, deactivate
the HOLD function in the following or similar
situations:
R when towing away
R in a car wash
Deactivating the HOLD function (Y page 155).
Activation conditions You can activate the HOLD function if:
R
the vehicle is stationary
R the engine is running or if it has been auto-
matically switched off by the ECO start/stop
function
R the driver's door is closed or if your seat belt
is fastened
R the electric parking brake is released
R the transmission is in position D,Ror N 154
Driving systemsDriving and parking

Activating the HOLD function
X
Make sure that the activation conditions are
met.
X Depress the brake pedal.
X Quickly depress the brake pedal further
until :appears in the multifunction display.
The HOLD function is activated. You can
release the brake pedal.
i If depressing the brake pedal the first time
does not activate the HOLD function, wait
briefly and then try again.
Deactivating the HOLD function The HOLD function is deactivated automatically
if:
R you accelerate. On vehicles with automatic
transmission: only when the transmission is in
position Dor R.
R the transmission is in position P.
R you depress the brake pedal again with a cer-
tain amount of pressure until :disappears
from the multifunction display.
R you secure the vehicle using the electric park-
ing brake.
i After a short period, the vehicle is secured
by the electric parking brake, thus relieving
the service brake.
The electric parking brake secures the vehicle
automatically if the HOLD function is activated
and:
R the driver's seat belt is not fastened and the
driver's door is open
R the engine is switched off, unless it is auto-
matically switched off by the ECO start/stop
function
R a system fault occurs
R the power supply is insufficient
The Brake immediately Brake immediately message may also
appear in the multifunction display. X
Immediately depress the brake pedal firmly
until the warning message in the multifunc-
tion display goes out.
The HOLD function is deactivated. A horn will
sound at regular intervals if you turn off the
engine, take off your seat belt or open the driv-
er's door when the HOLD function is activated.
The horn alerts you to the fact that the HOLD
function is still activated. If you attempt to lock
the vehicle, the tone becomes louder. The vehi- cle cannot be locked until you have deactivated
the HOLD function.
i Once you have switched off the engine, you
cannot restart it until you have deactivated
the HOLD function. PARKTRONIC
Important safety notes PARKTRONIC is an electronic parking aid with
ultrasonic sensors. It monitors the area around
your vehicle using six sensors in the front
bumper and six sensors in the rear bumper.
PARKTRONIC indicates visually and audibly the
distance between your vehicle and an object.
PARKTRONIC is only an aid. It is not a substitute for your attention to the immediate surround-
ings. The responsibility for safe manoeuvring
and parking remains with you. Make sure that
there are no persons, animals or objects in
range while manoeuvring and parking.
! When parking, pay particular attention to
objects above or below the sensors, such as
flower pots or trailer drawbars. PARKTRONIC does not detect such objects when they are in
the immediate vicinity of the vehicle. You
could damage the vehicle or the objects.
The sensors may not detect snow and objects which absorb ultrasonic sources.
Ultrasonic sources, such as an automatic car
wash, a lorry's compressed-air brakes or a
pneumatic drill, could cause PARKTRONIC to
malfunction.
PARKTRONIC may not function correctly on
uneven terrain. Driving systems
155Driving and parking Z

X
Select the assistance graphics display for
ATTENTION ASSIST using the on-board com-
puter (Y page 182).
The following information is displayed:
R the length of the journey since the last break
R the attention level determined by ATTENTION
ASSIST ( Attention level
Attention level), displayed in a
bar display in five levels from high to low
R if ATTENTION ASSIST is unable to calculate
the attention level and cannot issue a warn-
ing, the System suspended
System suspended message
appears. The bar display then changes the
display, e.g. if you are driving at a speed below 60 km/h or above 200 km/h.
Activating ATTENTION ASSIST X
Activate ATTENTION ASSIST using the on-
board computer (Y page 183).
The system determines the attention level of
the driver depending on the setting selected:
If Standard
Standard is selected: the sensitivity with
which the system determines the attention level
is set to normal.
If Sensitive Sensitive is selected: the sensitivity is set
higher. The attention level detected by ATTEN-
TION ASSIST is adapted accordingly and the
driver is warned earlier.
When ATTENTION ASSIST is deactivated, the
é symbol appears in the multifunction dis-
play in the assistance graphic display.
When ATTENTION ASSIST has been deactivated, it is automatically reactivated after the engine
has been switched off. The sensitivity selected
corresponds to the last selection activated
(standard/sensitive).
Warning in the multifunction display If fatigue or increasing lapses in concentration
are detected, a warning appears in the multi-
function display:
ATTENTION ASSIST ATTENTION ASSIST Take a
Take a
break!
break!.
In addition to the message shown in the multi-
function display, you will then hear a warning
tone.
X If necessary, take a break.
X Confirm the message by pressing the a
button on the steering wheel.
On long journeys, take regular breaks in good
time that allow for adequate recuperation. If you do not take a break and ATTENTION ASSIST still detects increasing lapses in concentration, you
will be warned again after 15 minutes at the
earliest. This will only happen if ATTEN-
TION ASSIST still detects typical indicators of
fatigue or increasing lapses in concentration.
If a warning is output in the multifunction dis-
play, a service station search is performed in
COMAND Online. You can select a service sta-
tion and navigation to this service station will
then begin. This function can be activated and
deactivated in COMAND Online. Traffic Sign Assist
General notes Traffic Sign Assist displays the maximum speed
permitted and overtaking restrictions to the
driver in the instrument cluster. Driving onto a
section of road in the wrong direction triggers a
warning. Traffic Sign Assist detects traffic signs with multifunction camera :attached at the
top of the windscreen. The data and general
traffic regulations stored in the navigation sys-
tem are also used to determine the current
speed limit.
If a traffic sign that is relevant to your vehicle is passed, the display of the speed limits and over-
taking restrictions is updated.
The display can also be updated without a visible traffic sign if:
R the vehicle changes roads (e.g. motorway exit
or slip road)
R a village or town boundary is passed which is
stored in the digital map
R the last traffic sign detected by the camera
has not been repeated
If a sign indicating the end of a restriction (speed limit or overtaking restriction) is passed, the
sign is displayed for five seconds. The currently 166
Driving systemsDriving and parking

E-CELL display
G
WARNING
There is a risk of an accident if you accelerate or overtake when the power output of the
drive system is reduced.
You should therefore adapt your driving style
and drive particularly carefully. Charge the
high-voltage battery at a charge station imme- diately. X
Start the drive system (Y page 128).
E-CELL display :shows the available power
of the drive system.
Under normal operating conditions, E-CELL dis-
play :is in the maximum range.
The power output available may deviate from
the maximum range in the event of:
R very high or low outside temperatures
R very high performance requirements for a lon-
ger period of time
R very low charge status of the high-voltage
battery
R a malfunction in the drive system
The reduced power output can be improved by
charging the high-voltage battery (Y page 134). Power display
Power display
:contains two areas:
R Area above 0
Here, the current amount of power that the
drive system is feeding to the wheels is dis-
played.
R Area below 0
Here, the vehicle's recuperative power in
overrun mode is displayed.
If the needle for the power display is in the OFF
position, the vehicle is not ready to drive
because:
R the drive system has not yet started
R the charging cable is still connected to the
vehicle socket
R there is insufficient power available from the
high-voltage battery
R the vehicle's high-voltage electrical system is
malfunctioning
When the drive system is started, the needle in
the power display moves to position 0. The dis-
play Ready
Ready appears in the lower multifunction
display. The vehicle is ready to drive.
The boost area for maximum acceleration can
be reached using kickdown (Y page 131).
The braking performance of the electric motor
using recuperative braking is, in some operating
modes, either reduced or not effective:
R when the charge status of the high-voltage
battery increases
R if the high-voltage battery is not yet at a nor-
mal operating temperature
R when driving close to the maximum speed
R when the vehicle is almost stationary
R in transmission position N
R during and after ESP stability control Displays and operation
173On-board computer and displays Z

If necessary, counteract the reduced regenera-
tive braking effect by applying the brake your-
self. Charge level display
Charge status display
:shows the charge sta-
tus of the high-voltage battery.
The charge value is shown as a percentage in the
energy flow
energy flow menu in the instrument cluster
(Y page 177).
i The
energy flow
energy flow menu can also be dis-
played n the COMAND/Audio display.
The charge level of the high-voltage battery has dropped into the reserve range if the drive sys-
tem is running and:
R the Drive battery Reserve level Drive battery Reserve level mes-
sage appears in the display
R the indicator lamp in the instrument cluster
lights up
Charge the high-voltage battery from a state of
charge of less than 20% at a:
R mains socket
R charging station
The braking performance of the electric motor
using recuperative braking is, in some operating
modes, either reduced or not effective:
R when the charge status of the high-voltage
battery increases
R if the high-voltage battery is not yet at a nor-
mal operating temperature
R when the vehicle is almost stationary
R in transmission position N
R during and after ESP stability control
If you do not make an additional effort to apply
the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative braking effect by applying the
brake yourself. Operating the on-board computer
Overview :
Multifunction display
; Right control panel
= Left control panel
X To activate the on-board computer: turn
the key to position 1in the ignition lock.
You can control the multifunction display and
the settings in the on-board computer using the buttons on the multifunction steering wheel.
Left control panel =
; R
Calls up the menu and menu bar 9
: Press briefly:
R Scrolls through lists
R Selects a submenu or function
R In the Audio Audio menu: selects the
previous or next station, when the preset list or station list is active,
or an audio track or video scene
R In the Tel Tel(Telephone) menu:
switches to the phone book and
selects a name or telephone num-
ber 174
Displays and operationOn-board computer and displays

Further information on the ECO display
(Y page 148).
Energy flow Energy flow display
The energy flow display can be shown in the
multifunction display and in the COMAND/
Audio display. X Press the =or; button on the steering
wheel to select the Trip Tripmenu.
X Confirm by pressing aon the steering
wheel.
X Use : or9 to select Energy flow
Energy flow .
The active components are highlighted in the
energy flow display.
The energy flow is indicated by arrows. The
arrows have a different colour depending on the
operating state:
R Green: energy recuperation
R White: normal energy consumption
R Red: increased energy consumption
Drive system switched on when the vehi-
cle is stationary or in overrun mode The drive system is switched on while the vehi-
cle is stationary. Alternatively, the drive system is switched on while the vehicle is in transmis-
sion position D+
or N.
There are no arrows indicating energy flow.
Drive system switched off and high-volt-
age battery being charged The drive system is switched off. The charging
cable is connected and the high-voltage battery
is being charged.
The arrows for the energy flow are shown in
green.
Normal driving The drive system powers the vehicle.
The arrows for the energy flow are shown in
white.
Boost driving mode If high power is required, the boost mode takes
effect.
The arrows for the energy flow are shown in red.
Energy recuperation mode The kinetic energy of the vehicle is converted
into electrical energy. The Recuperative Brake
System is active. The high-voltage battery is
charging.
The arrows for the energy flow are shown in
green. Menus and submenus
177On-board computer and displays Z

Safety systems
Display messages
Possible causes/consequences and
M
MSolutions !÷
currently unavaila‐
currently unavaila‐
ble ble See
SeeOwner's
Owner's Man‐
Man‐
ual
ual ABS (Anti-lock Braking System), BAS (Brake Assist), ESP
®
(Electronic
Stability Program), the HOLD function, RBS (Recuperative Brake Sys-
tem), hill start assist and PRE-SAFE ®
are temporarily unavailable.
The adaptive brake lights and COLLISION PREVENTION ASSIST PLUS
may also have failed.
The !, ÷,åandJ warning lamps may also light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
Possible causes:
R Self-diagnosis is not yet complete
R The on-board voltage may be insufficient.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not be sufficient. If necessary, counteract the reduced regenerative brak-
ing effect by applying the brake yourself.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The steerability and braking characteristics may be severely affected. The braking distance may increase in an emergency braking situation.
If ESP ®
is not operational, ESP ®
is unable to stabilise the vehicle.
There is an increased danger of skidding and risk of an accident.
X Carefully drive on a suitable stretch of road, making slight steering
movements, at a speed above 20 km/h.
If the display message disappears, the functions mentioned above
are available again.
If the multifunction display still shows the display message:
X Drive on carefully.
X Consult a qualified specialist workshop immediately. !÷
inoperative inoperative See
SeeOwn‐
Own‐
er's Manual
er's Manual ABS, BAS, ESP
®
, the HOLD function, RBS, hill start assist and
PRE‑SAFE ®
are not available due to a malfunction.
The adaptive brake lights and COLLISION PREVENTION ASSIST PLUS
may also have failed.
The !, ÷,åandJ warning lamps may also light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
G WARNING
The braking performance of the electric motor using recuperative
braking may be either reduced or not effective. If you do not make an
additional effort to apply the brake yourself, the braking effect may not 190
Display messagesOn-board computer and displays