2008 MERCEDES-BENZ C300 Keyless start

424 Practical hints
Unlocking/locking in an emergency
Unlocking the vehicle
If you cannot unlock the vehicle with the
SmartKey or KEYLESS-GO* (Canada only),
unlock the driver’s door and the trunk us-
ing the mechanical key. Removing the mechanical key
1Mechanical key locking tab
2Mechanical key
Move locking tab1 in the direction of
arrow.
Slide mechanical key2 out of the
housing.Unlocking the driver’s door
Insert mechanical key2 into the driv-
er’s door lock until it stops.
Turn mechanical key2 counterclock-
wise to position 1.
The locking knob moves up, the driver’s
door is unlocked.
Pull the door handle to open the driv-
er’s door.
iUnlocking the vehicle with the mechanical
key and opening the driver’s door or the trunk
with the mechanical key will trigger the anti-theft
alarm system (
page 66).
To cancel the alarm, insert the SmartKey or
SmartKey with KEYLESS-GO* (Canada only) in
the starter switch.
1Unlocking
2Mechanical key

438 Practical hints
Replacing wiper blades
Warning!G
For safety reasons, switch off wipers and re-
move SmartKey from starter switch (vehi-
cles with KEYLESS-GO* (Canada only):
Make sure the vehicle’s on-board electron-
ics have status0) before replacing a wiper
blade. Otherwise, the wiper motor could
suddenly turn on and cause injury.
Warning!G
Wiper blades are components that are sub-
ject to wear and tear. Change the wiper
blades twice a year, preferably in the spring
and fall. Otherwise the windows will not be
properly wiped. As a result, you may not be
able to observe surrounding traffic condi-
tions and could cause an accident.
!To avoid damage to the hood, never open
the hood when the wiper arm is folded forward.
!Hold on to the wiper when folding the wiper
arm back. If released, the force of the impact
from the tensioning spring could crack the wind-
shield.
Do not allow the wiper arms to contact the wind-
shield glass without a wiper blade inserted.
For your convenience, we recommend that you
have this work carried out at an authorized
Mercedes-Benz Center.

440 Practical hints
Flat tire
Preparing the vehicle
Park the vehicle in a safe distance from
moving traffic on a hard, flat surface
when possible.
Turn on the hazard warning flashers.
Turn the steering wheel so that the
front wheels are in a straight-ahead
position.
Set the parking brake.
Vehicles with automatic transmission*:
Move the gear selector lever to
positionP (
page 138).
Turn off the engine (page 134).
Remove the SmartKey from the starter
switch.
Vehicles with KEYLESS-GO*:
Turn off the engine by pressing the
KEYLESS-GO* button once
(
page 135).
Open the driver’s door (this puts
the starter switch in position0,
same as with the SmartKey re-
moved from the starter switch). The
driver’s door then can be closed
again.
Have any passenger exit the vehicle at
a safe distance from the roadway.
Warning!G
The dimensions of the Minispare wheel are
different from those of the road wheels. As
a result, the vehicle handling characteristics
change when driving with a Minispare wheel
mounted. Adapt your driving style
accordingly.
The Minispare wheel is for temporary use
only. When driving with Minispare wheel
mounted, ensure proper tire inflation
pressure and do not exceed a vehicle speed
of 50 mph (80 km/h).
Contact the nearest Mercedes-Benz Center
as soon as possible to have the Minispare
wheel replaced with a regular road wheel.
Never operate the vehicle with more than
one Minispare wheel mounted.
Do not switch off the ESP
® with a Minispare
wheel mounted.
iOpen the door only when conditions are safe
to do so.

448 Practical hints
Battery
Starter battery
1Battery
2Positive terminal
3Negative terminal
4Ventilation hose
Disconnecting the battery
Apply the parking brake (page 134).
Make sure gear selector lever* is set to
positionP (manual transmission to
Neutral).
Turn off all electrical consumers.
Remove SmartKey from starter switch.Vehicles with KEYLESS-GO* (Canada
only):
Press the start / stop button until
the engine shuts off.
Open the driver’s door.
Open the hood (page 325).
Remove the filter box (page 447).
Read and observe safety instructions
and precautions (
page 446).
Disconnect the battery negative lead
from negative terminal3.
Remove cover from the positive
terminal2.
Disconnect the battery positive lead.iIf the battery is discharged, you must use
the mechanical key to unlock (
page 424) or
lock (
page 425) the vehicle.
Warning!G
With a disconnected battery

you will no longer be able to turn the
SmartKey in the starter switch and
pressing the KEYLESS-GO* start/stop
button (Canada only) will have no effect

vehicles with automatic transmission*:
the gear selector lever will remain
locked in positionP
!Always disconnect the starter battery in the
order described below. You could otherwise
damage the vehicle’s electronics.

450 Practical hints
Battery
Reconnecting the battery
Turn off all electrical consumers.
Remove SmartKey from starter switch.
Vehicles with KEYLESS-GO* (Canada
only):
Open the driver’s door.
Connect the battery positive lead and
fasten its cover (
page 448).
Connect the battery negative lead
(
page 448).
Make sure that the ventilation hose4
is attached to the battery.
Reinstall filter box (page 447).
!Always connect the starter battery in the or-
der described below. Otherwise, the vehicle’s
electronics could be damaged.
!Never invert the terminal connections.
!Make sure the battery has a plug where the
ventilation hose
4 is attached to it.
iThe following procedures must be carried
out following any interruption of battery power
(e.g. due to reconnecting):

Reset the automatic exterior mirror fold in
function (
page 99).

Set the clock (page 170).
Vehicles with COMAND*: see COMAND op-
erator’s manual.

453 Practical hints
Towing the vehicle
Towing the vehicle
Mercedes-Benz recommends that the
vehicle be transported with all wheels off
the ground using flatbed or appropriate
wheel lift/dolly equipment. This method is
preferable to other types of towing.When circumstances do not permit the
recommended towing methods, the
vehicle may be towed with all wheels on
the ground or front wheels raised (except
vehicles with 4MATIC) only so far as neces-
sary to have the vehicle moved to a safe
location where the recommended towing
methods can be employed.
When towing the vehicle with all wheels on
the ground or the front axle raised (not per-
missible for vehicles with 4MATIC), the ve-
hicle may be towed only for distances up to
30 miles (50 km) and at a speed not to ex-
ceed 30 mph (50 km/h).
!Vehicles with automatic transmission*
and/or 4MATIC:
Do not tow-start the vehicle.
!Use flatbed or wheel lift/dolly equipment
with SmartKey or SmartKey with KEYLESS-GO*
(Canada only) in starter switch turned to
position0.
Do not tow with sling-type equipment. Towing
with sling-type equipment over bumpy roads will
damage radiator and supports.
To prevent damage during transport, do not tie
down vehicle by its chassis or suspension parts.
Switch off the ESP
® (page 63) and the auto-
matic central locking (
page 173).
!Vehicles with 4MATIC:
Do not tow with one axle raised. Doing so could
damage the transfer case, which is not covered
by the Mercedes-Benz Limited Warranty.
All wheels must be on or off the ground. Observe
instructions for towing the vehicle with all
wheels on the ground.
Warning!G
If circumstances require towing the vehicle
with all wheels on the ground, always tow
with a tow bar if:

the engine will not run

there is a malfunction in the brake
system

there is a malfunction in the power
supply or in the vehicle’s electrical
system
This is necessary to adequately control the
towed vehicle.
Prior to towing the vehicle with all wheels on
the ground, make sure the SmartKey or
SmartKey with KEYLESS-GO* (Canada only)
is in starter switch position2.

454 Practical hints
Towing the vehicle
Warning!G
Without the engine running, there is no pow-
er assistance for the brake and steering sys-
tems. In this case, it is important to keep in
mind that a considerably higher degree of
effort is necessary to brake and steer the
vehicle. Adapt your driving accordingly.
iWhen towing the vehicle with all wheels on
the ground, please note the following:
With the automatic central locking activated and
the SmartKey or SmartKey with KEYLESS-GO*
(Canada only) in starter switch position 2, the ve-
hicle doors lock if the left front wheel as well as
the right rear wheel are turning at vehicle speeds
of approximately 9 mph (15 km/h) or more.
To prevent the vehicle doors from locking,
deactivate the automatic central locking
(
page 173).
!If the vehicle is towed with the front axle
raised (not permissible for vehicles with
4MATIC), the gear selector lever must be in
positionN (manual transmission: gear shift lever
in neutral position) and the engine must be shut
off (SmartKey or SmartKey with KEYLESS-GO*
(Canada only) in starter switch position0 or1).
Active braking action through the ESP
® may
otherwise seriously damage the brake system.
While towing, the battery must be connected and
charged. Otherwise:

you will not be able to switch on the ignition

you will not be able to engage the automatic
transmission* in positionN (
page 127)
When towing the vehicle with all wheels on the
ground, the gear selector lever must be in
positionN (manual transmission: gear shift lever
in neutral position) and the SmartKey or
SmartKey with KEYLESS-GO* (Canada only)
must be in starter switch position2.
!Towing of the vehicle should only be done
using the properly installed towing eye bolt.
Never attach tow cable, tow rope or tow rod to
vehicle chassis, frame or suspension parts.
iTo signal turns while being towed with the
hazard warning flasher in use, turn SmartKey or
SmartKey with KEYLESS-GO* (Canada only) in
starter switch to position2 and activate the
combination switch for the left or right turn sig-
nal in the usual manner – only the selected turn
signal will operate.
Upon canceling the turn signal, the hazard
warning flasher will operate again.
!Make sure the parking brake is released.
iIf the battery is disconnected or discharged

the SmartKey or SmartKey with KEY-
LESS-GO* (Canada only) will not turn in the
starter switch

Vehicles with automatic transmission*: the
gear selector lever will remain locked in
positionP (
page 127).
For more information see “Battery”
(
page 446) and see “Jump starting”
(
page 451).

456 Practical hints
Fuses
The electrical fuses in your vehicle serve to
switch off malfunctioning power circuits.
If a fuse is blown, the component(s) and
systems secured by that fuse will stop op-
erating.If a newly inserted fuse blows again, have
the cause determined and rectified at an
authorized Mercedes-Benz Center.
A fuse chart explains the fuse allocation
and fuse amperages. It is located in the
main fuse box in the passenger compart-
ment (
page 457).
The electrical fuses are located in different
fuse boxes:

Fuse box in passenger compartment
(
page 457)

Fuse box in engine compartment
(
page 457)

Fuse box in trunk (page 458)Before replacing fuses:
Depress the parking brake
(
page 134).
Make sure the manual transmission is
in Neutral (
page 136), automatic
transmission* is set to P (
page 140).
The gear position indicator in the ta-
chometer display should be on P.
Turn off all electrical consumers.
Turn off the engine (page 134).
Remove the SmartKey from the starter
switch.
Vehicles with KEYLESS-GO*
(Canada only):
Open the driver’s door.
Warning!G
Only use fuses approved by Mercedes-Benz
with the specified amperage for the system
in question and do not attempt to repair or
bridge a blown fuse. Using other than ap-
proved fuses or using repaired or bridged
fuses may cause an overload leading to a
fire, and/or cause damage to electrical
components and/or systems. Have the
cause determined and remedied at an au-
thorized Mercedes-Benz Center.
iA blown fuse must be replaced by an appro-
priate spare fuse (recognizable by its color or the
fuse rating given on the fuse) of the amperage
recommended in the fuse chart.
Any Mercedes-Benz Center will be glad to advise
you on this subject.
!Switch off the vehicle’s internal electrical
functions (
page 448) when you are working on
the fuses.
iIn case of a blown fuse contact Roadside
Assistance or an authorized Mercedes-Benz
Center.