lights MERCEDES-BENZ B-CLASS HATCHBACK 2008 Service Manual

Troubleshooting
222 Troubleshooting
Points to remember
G
Risk of accident and injury
The operating safety of your vehicle could be compromised if service work is carried out improperly. You could lose control of the vehicle,
thereby causing an accident. Safety systems may also not be able to protect you or others as intended.
Always have maintenance work carried out at a qualified specialist workshop which has the necessary specialist knowledge and tools to
carry out the work required.
Mercedes-Benz recommends that you use a Mercedes-Benz Service Centre for this purpose.
In particular, work relevant to safety or on safety-related systems must be carried out at a qualified specialist workshop. Warning and indicator lamps in switches and buttons
Problem Possible cause/consequence Suggested solutions
One or all of the indicator lamps
in the seat heating* button are
flashing. The seat heating* has
switched itself off automatically. The on-board voltage is too low,
because too many consumers are
switched on. X
Switch off consumers that are not required, e. g. reading lamp or
interior lighting.
Once the battery is sufficiently charged, the seat ventilation* will
switch back on automatically. The indicator lamp in the
2
button on the air-conditioning */
Ther motronic* control panel
lights up. The cooling system can-
not be switched on. Cooling has been deactivated
due to a malfunction. X
Visit a qualified specialist workshop. Practical advice
* optional
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Troubleshooting
227Problem Possible cause/consequence Suggested solutions
H
The red brake system
warning lamp comes on
while the engine is run-
ning. G
Risk of accident
There is insufficient brake fluid in
the fluid reservoir. X
Pull over and stop the vehicle safely, paying attention to road and
traffic conditions. Do not continue driving under any circumstan-
ces.
X Consult a qualified specialist workshop immediately.
X Observe the additional messages in the multi-function display
(Y page 202).
Do not top up the brake fluid. This will not rectify the fault. ±
The yellow engine diagnos-
tics warning lamp lights up
while the engine is run-
ning. Vehicles with a diesel engine: the
fuel tank has been run dry. X
Start the engine three to four times after refuelling.
Emergency running mode is cancelled. The vehicle need not be
checked. ±
The yellow engine diagnos-
tics warning lamp lights up
while the engine is run-
ning. There may be a fault, for example
R
in the engine management
R in the ignition system
R in the exhaust system
R in the ignition system (for vehi-
cles with petrol engines)
The emission limit values may be
exceeded and the engine can run
in emergency mode. X
Have the vehicle checked as soon as possible at a qualified spe-
cialist workshop. Practical advice
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Troubleshooting
228 Problem Possible cause/consequence Suggested solutions
<
The red seat belt warning
lamp lights up for 6 sec-
onds after the engine
starts up 28
. The seat belt warning lamp
reminds the driver and front
passenger to fasten their seat
belts. X
Fasten your seat belt (Y page 72).<
After the engine starts, a
warning tone sounds for
up to 6 seconds 28
. G
Risk of injury
The driver's seat belt is not fas-
tened. X
Fasten your seat belt (Y page 72).
The warning tone ceases. <
The red seat belt warning
lamp lights up after the
engine starts, as soon as
the driver's door or the
front-passenger door is
closed. G
Risk of injury
The driver or front passenger has
not fastened their seat belt X
Fasten your seat belt (Y page 72).
The warning lamp goes out. G
Risk of injury
There are objects on the front-
passenger seat X
Remove the objects from the front-passenger seat and stow them
safely.
The warning lamp goes out. 28
Only for certain countries. Practical advice
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Troubleshooting
229Problem Possible cause/consequence Suggested solutions
<
The red warning lamp
flashes and an intermit-
tent audible warning
sounds. G
Risk of injury
The driver or front passenger has
not fastened their seat belt and
you are driving faster than
25 km/h or have briefly driven
faster than 25 km/h. X
Fasten your seat belt (Y page 72).
The warning lamp goes out and the intermittent audible warning
ceases. G
Risk of injury
There are objects on the front-
passenger seat and you are driv-
ing faster than 25 km/h or have
briefly driven faster than
25 km/h. X
Remove the objects from the front-passenger seat and stow them
safely.
The warning lamp goes out and the intermittent audible warning
ceases. The yellow engine diagnostics
warning lamp lights up while the
engine is running. The fuel level has fallen below the
reserve range. X
Refuel at the nearest filling station. Practical advice
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Troubleshooting
236 Parktronic*
Problem Possible cause/consequence Suggested solutions
Only the red segments in the
Parktronic warning display are lit.
You also hear a warning tone for
approximately two seconds.
Parktronic is deactivated after
approximately 20 seconds and
the indicator lamp in the Park-
tronic button lights up. Parktronic has malfunctioned
and has switched itself off. X
If problems persist, have Parktronic checked at a qualified spe-
cialist workshop. Only the red segments in the
Parktronic warning display are lit.
Parktronic is deactivated after
approximately 20 seconds. The Parktronic sensors are dirty
or there is interference. X
Clean the Parktronic sensors ( Ypage 196).
X Switch the ignition back on. Only the red segments in the
Parktronic warning display are lit.
Parktronic is deactivated after
approximately 20 seconds. The problem may be caused by an
external source of radio or ultra-
sound waves. X
See if Parktronic functions in a different location. Practical advice
* optional
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Changing bulbs
244 Key
Checking the batteries X
Press the jork button.
The batteries are in order if the battery
charge indicator lamp lights up briefly.
Changing the batteries You require two CR 2025 3 V cell batteries.
X Remove the emergency key element from
the key (Y page 241). 1
Emergency key element
2 To release the battery tray
3 To pull out the battery tray
4 Battery tray X
Using emergency key element 1, press
the grey release catch in the opening in the
direction of arrow 2.
Battery tray 4is released.
X Pull battery tray 4out of the key in the
direction of arrow 3. X
Remove old batteries 1from the battery
tray.
X Insert the new batteries underneath con-
tact spring 2with the positive terminal
facing upwards. Use a lint-free cloth to do
so.
X Push the battery tray back into the key
housing until the battery tray engages.
X Check the function of all key buttons on the
vehicle. Changing bulbs
Notes on changing bulbs
Bulbs and lamps are an important aspect of
vehicle safety. You must therefore make sure
that these function correctly at all times. G
Risk of injury
Bulbs and lamps can be very hot. You
should therefore allow them to cool down
before you change them. Otherwise, you
could be burned if you touch them.
Keep bulbs out of the reach of children.
Otherwise, they could damage them, for
example, and injure themselves.
Never use a bulb which has been dropped.
Such a bulb may explode and injure you.
H7 bulbs are pressurised and could explode
when you change them, particularly if they
are very hot. You should therefore wear eye
protection and gloves when you are chang-
ing them. G
Risk of injury
Xenon bulbs carry a high voltage. You could
get an electric shock and be seriously or
even fatally injured if you touch the electric
contacts on xenon bulbs. Therefore, never
remove the cover from xenon bulbs. Practical advice
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Changing bulbs
246
Rear bulbs Bulb Type
7
Third brake
lamp LED
8
Turn signal lamp PY 21 W
9
Reversing lamp P 21 W
a
Licence plate
lamp C 5 W
b
Rear foglamp P 21 W
c
Tail lamp P 5 W
d
Brake lamp P 21 W
Before changing bulbs
You can replace the following bulbs:
R
Dipped-beam headlamps (halogen head-
lamps)
R Main-beam headlamps (halogen head-
lamps)
R Side lamp/parking lamp
R Cornering light* (vehicles with bi-xenon
headlamps *)
R Front turn signal lamp R
Brake lamp
R Tail lamp
R Turn signal lamp (rear)
R Licence plate lamp
Observe the following points:
R Use only the bulb types specified here.
R To prevent a short-circuit, switch off the
lights before changing a bulb.
R Only hold bulbs with a clean, lint-free cloth.
R Do not work with wet or greasy fingers.
R If the new bulb still does not light up, con-
sult a qualified specialist workshop, e.g. a
Mercedes-Benz Service Centre.
i Due to the location of the bulbs in the
front headlamps, it is best to have these
changed at a qualified specialist workshop,
e.g. a Mercedes-Benz Service Centre.
i Have the headlamp setting checked reg-
ularly at a qualified specialist workshop,
e.g. a Mercedes-Benz Service Centre. Changing the front bulbs
Removing/fitting the washer fluid res-
ervoir You must remove the washer fluid reservoir
from the engine compartment before you can
replace the bulbs in the front left-hand head-
lamp.
X
To remove: turn retaining screw 1anti-
clockwise.
X Remove washer fluid reservoir 2from
bracket 3.
X Put washer fluid reservoir 2to one side
and leave the lines and hoses connected.
Make sure that no washer fluid escapes.
X To fit: guide the lower retaining lug into the
rubber grommet on the longitudinal mem- Practical advice
* optional
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Changing bulbs
247
ber and fit washer fluid reservoir
2into
bracket 3.
X Turn retaining screw 1clockwise.
Replacing the bulbs in the dipped-beam
headlamp (halogen headlamps) X
Switch off the lights.
X Open the bonnet.
X Left-hand headlamps: remove the washer
fluid reservoir (Y page 246).
X Press retaining lug 1down and remove
housing cover 2.
X Pull connector 3from bulb 5.
X Detach retaining spring 4and remove
bulb 5.
X Insert the new bulb so that it is flush. X
Attach retaining spring 4.
X Attach connector 3to bulb 5.
X Align the bottom of housing cover 2and
fold it upwards until it engages.
Main-beam headlamps (halogen head-
lamps)/cornering light*(bi-xenon head-
lamps*) X
Switch off the lights.
X Open the bonnet.
X Left-hand headlamp: remove the washer
fluid reservoir (Y page 246).
X Press retaining lug 1down and remove
housing cover 2.
X Pull connector 3from housing cover 4.X
Turn housing cover 4anti-clockwise and
remove it.
X Remove the bulb.
X Insert the new bulb so that it is flush.
X Turn housing cover 4clockwise.
X Attach connector 3to housing cover 4.
X Align the bottom of housing cover 2and
fold it upwards until it engages.
Replacing side lamp/parking lamp
bulbs X
Switch off the lights.
X Open the bonnet.
X Left-hand headlamp: remove the washer
fluid reservoir (Y page 246). Practical advice
* optional
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Changing bulbs
248
X
Press retaining lug 1down and remove
housing cover 2.
X Pull out bulb holder 3.
X Turn the bulb anti-clockwise, applying
slight pressure, and remove it from bulb
holder 3.
X Insert the new bulb into bulb holder 3and
turn clockwise while applying slight pres-
sure.
X Insert bulb holder 3.
X Align the bottom of housing cover 2and
fold it upwards until it engages.
Replacing the turn signal lamps X
Switch off the lights.
X Open the bonnet. X
Left-hand headlamp: remove the washer
fluid reservoir (Y page 246).
X Turn bulb holder 1anti-clockwise and pull
it out.
X Turn the bulb anti-clockwise, applying
slight pressure, and remove it from bulb
holder 1.
X Insert the new bulb into bulb holder 1and
turn clockwise while applying slight pres-
sure.
X Insert bulb holder 1and turn it clockwise. Changing the rear bulbs
Opening and closing the side trim pan-
els You must open the side trim panel in the lug-
gage compartment before you can change
the bulbs in the tail lamps. Left-hand side trim panel
Right-hand side trim panelPractical advice
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Changing bulbs
249
Opening
X
Turn release catch 190° in the direction
of the arrow and remove side trim panel
2.
X Left side: remove the first-aid kit.
X Right side: remove the stowage compart-
ment.
Closing
X Left side: insert the first-aid kit.
X Right side: insert the stowage compart-
ment.
X Insert side trim panel 2and turn catch
1 90° in the opposite direction to the
arrow.
Changing the tail lamps X
Switch off the lights.
X Open the luggage compartment.
X Open the side trim panel (Y page 248). Bulb holder
X
Press retaining lugs 1simultaneously in
the direction of the arrow and pull the bulb
holder out. Bulb holder
1
Brake lamp
2 Turn signal lamp
3 Tail lamp
X Lightly press the corresponding bulb into
the holder, turn it anti-clockwise and
remove it from the bulb holder.
X Insert the corresponding new bulb into the
bulb holder and turn it clockwise.
X Attach the bulb holder and press firmly.
The retaining lugs on the bulb holder
engages audibly.
X Close the side trim panel (Y page 248). Practical advice
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