2012 MERCEDES-BENZ S-Class ECU

XPrepare the vehicle as described
( Y page 473).XRemove the following items (depending on
the vehicle's equipment) from the stowage
well under the trunk floor:
R the emergency spare wheel or spare
wheel
R wheel bolts for the spare wheel/
emergency spare wheel
R the vehicle tool kit
R the folding wheel chock
R the jackXSecure the vehicle to prevent it from rolling
away.
Securing the vehicle to prevent it from
rolling away
GWARNING
Only jack up the vehicle on level ground or on
slight inclines/declines. The vehicle could
otherwise fall off the jack and injure you or
others.
If your vehicle is equipped with a wheel chock,
it can be found in the vehicle tool kit
( Y page 472).
The folding wheel chock is an additional
securing measure to prevent the vehicle from
rolling away, for example when changing a
wheel.
XFold both plates upwards :.XFold out lower plate ;.XGuide the lugs on the lower plate fully into
the openings in base plate =.
Securing the vehicle on level ground
XOn level ground: place chocks or other
suitable items under the front and rear of
the wheel that is diagonally opposite the
wheel you wish to change.
Securing the vehicle on slight downhill gradients
XOn downhill gradients: place chocks or
other suitable items in front of the wheels
of the front and rear axle.
Raising the vehicle
GWARNING
When jacking up the vehicle, only use the jack
which has been specifically approved by
Mercedes-Benz for your vehicle.
The jack is designed exclusively for jacking up
the vehicle at the jacking points built into both
sides of the vehicle. The jack saddle must be
474Flat tireBreakdown assistance

light-alloy wheel. Using other wheel bolts
when fitting the "Minispare" emergency
spare wheel with light-alloy wheel could
damage the brake system.
Always use wheel bolts ; to fit the
"Minispare" emergency spare wheel with
steel wheel. Using other wheels when
fitting the "Minispare" emergency spare
wheel with steel wheel could damage the
brake system.XClean the wheel and wheel hub contact
surfaces.
! To prevent damage to the paintwork, hold
the wheel securely against the wheel hub
while screwing in the first wheel bolt.
XSlide the emergency spare wheel onto the
alignment bolt and push it on.XTighten the wheel bolts until they are
finger-tight.XUnscrew the alignment bolt.XTighten the last wheel bolt until it is finger-
tight.
Lowering the vehicle
XTurn the crank of the jack counter-
clockwise until the vehicle is once again
standing firmly on the ground.XPlace the jack to one side.XTighten the wheel bolts evenly in a
crosswise pattern in the sequence
indicated ( : to A). The tightening torque
must be 110 lb-ft (150 Nm) .GWARNING
Have the tightening torque checked
immediately after a wheel is changed. The
wheels could come loose if they are not
tightened to a torque of 110 lb/ft
(150 Nm) .
XTurn the jack back to its initial position and
store it together with the rest of the tire-
change tool kit in the stowage well under
the trunk floor.
i When you are driving with the emergency
spare wheel mounted, the tire pressure
monitoring system cannot function
reliably. Only restart the tire pressure
monitoring system when the defective
wheel has been replaced with a new wheel.
All mounted wheels must be equipped with
functioning sensors and the defective
wheel should no longer be in the vehicle.
MOExtended tires (tires with run-flat
properties)
MOExtended tires (tires with run-flat
properties) allow you to continue driving your
vehicle even if one or more tires are entirely
deflated.
MOExtended tires may only be used in
conjunction with the activated tire pressure
Flat tire477Breakdown assistanceZ

! Like other batteries, the vehicle battery
may discharge over time if you do not use
the vehicle. In this case have the battery
checked at a qualified specialist workshop,
such as an authorized Mercedes-Benz
Center. You can also charge the battery
with a charger recommended by Mercedes-
Benz. Contact an authorized Mercedes-
Benz Center for more information.
The battery and the cover of the positive
terminal clamp must be installed securely
during operation.
i Remove the SmartKey if you park the
vehicle and do not require any electrical
consumers. The vehicle will then use very
little energy, thus conserving battery
power.
Mercedes-Benz recommends that you do not
carry out work on batteries yourself, e.g.
removing or charging. Always have this work
performed at a qualified specialist workshop,
e.g. an authorized Mercedes-Benz Center.
Charging the battery
GWARNING
Never charge a battery still installed in the
vehicle unless a battery charger unit approved
by Mercedes-Benz is being used. Gases may
escape during charging and cause explosions
that may result in paint damage, corrosion or
personal injury.
A battery charger unit specially adapted for
Mercedes-Benz vehicles and tested and
approved by Mercedes-Benz is available as an
accessory. It permits the charging of the
battery in its installed position. Contact an
authorized Mercedes-Benz Center for further
information and availability.
Charge the battery in accordance with the
separate instructions for the battery charger.
GWARNING
There is a risk of acid burns during the
charging process due to the gases which
escape from the battery. Do not lean over the
battery during the charging process.GWARNING
Battery acid is caustic. Avoid contact with the
skin, eyes or clothing.
! Only charge the installed battery with a
battery charger which has been tested and
approved by Mercedes-Benz. These battery
chargers allow the battery to be charged
while still installed.
! Only use battery chargers with a
maximum charging voltage of 14.8 V.
! Only charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment ( Y page 481).
XOpen the hood ( Y page 456).XConnect the battery charger to the positive
terminal and earth point in the same order
as when connecting the donor battery in
the jump-starting procedure
( Y page 481).XRead the battery charger's operating
instructions before charging the battery.480BatteryBreakdown assistance

XMake sure that the two vehicles do not touch.XSecure the vehicle by applying the electric parking brake.XShift the transmission to position P.XSwitch off all electrical consumers (e.g. radio, blower, etc.).XOpen the hood ( Y page 456).
Position number A identifies the charged battery of the other vehicle or an equivalent jump-
starting device.
XRemove the cover from positive terminal :.XConnect positive terminal : on your vehicle to positive terminal ; of donor battery A
using the jumper cable, beginning with your own battery.XStart the engine of the donor vehicle and run it at idling speed.XConnect negative terminal = of donor battery A to earth point ? of your vehicle using
the jumper cable, connecting the jumper cable to donor battery A first.XStart the engine.XAllow the engine to run for a few minutes before disconnecting the jumper cable.XFirst, remove the jumper cable from earth point ? and negative terminal =, then from
positive terminal : and positive terminal ;, each time disconnecting from the battery on
your own vehicle first.XHave the battery checked at a qualified specialist workshop, e.g. an authorized Mercedes-
Benz Center. The jump-starting procedure is not a standard operating state; therefore, have
the battery checked.482Jump-startingBreakdown assistance

Towing and tow-starting
Important safety notes
GWARNING
Hybrid vehicles: be sure to read the "HYBRID"
supplement. Otherwise, you could fail to
recognize dangers.
GWARNING
If you tow the vehicle, you must use a rigid
towing bar if:
R the engine is not running.
R there is a brake system malfunction.
R there is a malfunction in the power supply
or the vehicle's electrical system.
The power assistance for the steering and the
brake force booster do not work when the
engine is not running. You will need more
force to steer and brake, you may have to
depress the brake pedal with maximum force.
Before towing away, make sure that the
steering can be moved and is not locked.
If you tow or tow-start another vehicle, its
weight must not exceed the maximum
permissible gross vehicle weight of your
vehicle.
GWARNING
The vehicle is braked when the HOLD function
or DISTRONIC PLUS is activated. Therefore,
deactivate HOLD and DISTRONIC PLUS if the
vehicle is to be towed.
It is better to have the vehicle transported
than to have it towed.
! You may only tow the vehicle a maximum
distance of 30 miles (50 km). A towing
speed of 30 mph (50 km/h) must not be
exceeded.
For towing distances over 30 miles
(50 km), the vehicle must loaded onto a
transporter.
! Make sure that the electric parking brake
is released. If the electric parking brake is
faulty, visit a qualified specialist workshop.
! Only secure the tow rope or tow bar at the
towing eyes. Otherwise, the vehicle could
be damaged.
! Do not use the towing eye for recovery,
as this could damage the vehicle. If in
doubt, recover the vehicle with a crane.
! When towing, pull away slowly and
smoothly. If the tractive power is too high,
the vehicles could be damaged.
! Do not tow with sling-type equipment.
This could damage the vehicle.
! When towing vehicles with KEYLESS-GO,
use the key instead of the Start/Stop
button. Otherwise, the automatic
transmission may shift to position P when
the driver's or front-passenger door are
opened, which could lead to damage to the
transmission.
The automatic transmission must be in
position N when the vehicle is being towed.
The battery must be connected and charged.
Otherwise, you:
R cannot turn the SmartKey to position 2 in
the ignition lock
R cannot shift the automatic transmission to
position N
i Before the vehicle is towed, switch off the
automatic locking feature ( Y page 264).
You could otherwise be locked out when
pushing or towing the vehicle.
Installing/removing the towing eye
Installing the towing eye
XRemove the towing eye from the vehicle
tool kit ( Y page 472).GWARNING
The exhaust tail pipe may be hot. You could
burn yourself if you touch the tail pipe. Be
particularly careful when removing the rear
cover.
Towing and tow-starting483Breakdown assistanceZ

Transporting the vehicle
The towing eye can be used to pull the vehicle
onto a trailer or transporter for transporting
purposes.XTurn the SmartKey to position 2 in the
ignition lock.XShift the automatic transmission to
position N.
As soon as the vehicle is loaded:
XPrevent the vehicle from rolling away by
applying the electric parking brake.XShift the automatic transmission to
position P.XTurn the SmartKey to position 0 in the
ignition lock and remove the SmartKey
from the ignition lock.XSecure the vehicle.
! Only lash the vehicle down by the wheels
or wheel rims, not by parts of the vehicle
such as axle or steering components.
Otherwise, the vehicle could be damaged.
Notes for 4MATIC vehicles
! Vehicles with 4MATIC must not be towed
with either the front or the rear axle raised,
as doing so will damage the transmission.
If the vehicle has transmission damage or
damage to the front or rear axle, have it
transported on a transporter or trailer.
In the event of damage to the electrical
system
If the battery is defective, the automatic
transmission will be locked in position P. To
shift the automatic transmission to position
N , you must provide power to the vehicle's
electrical system in the same way as when
jump-starting ( Y page 481).
Have the vehicle transported on a transporter
or trailer.
Tow-starting (emergency starting)
! Vehicles with automatic transmission
must not be started by tow-starting. This
could otherwise damage the transmission.
Fuses
Important safety notes
The fuses in your vehicle serve to close down
faulty circuits. If a fuse blows, all the
components on the circuit and their functions
stop operating.
GWARNING
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
approved 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 by an authorized
Mercedes-Benz Center.
Blown fuses must be replaced with fuses of
the same rating, which you can recognize by
the color and value. The fuse ratings are listed
in the fuse allocation chart. An authorized
Mercedes-Benz Center will be happy to
advise you.
i If a fuse has blown, contact a breakdown
service or an authorized Mercedes-Benz
Center.
If the newly inserted fuse also blows, have the
cause traced and rectified at a qualified
specialist workshop, e.g. an authorized
Mercedes-Benz Center.
! Only use fuses that have been approved
for Mercedes-Benz vehicles and which
have the correct fuse rating for the system
concerned. Otherwise, components or
systems could be damaged.
Fuses485Breakdown assistanceZ

Checking the tire pressures
Important safety notesGWARNING
Follow recommended tire inflation pressures.
Do not underinflate tires. Underinflated tires
wear excessively and/or unevenly, adversely
affect handling and fuel economy, and are
more likely to fail from being overheated.
Do not overinflate tires. Overinflated tires can
adversely affect handling and ride comfort,
wear unevenly, increase stopping distance,
and result in sudden deflation (blowout)
because they are more likely to become
punctured or damaged by road debris,
potholes etc.
Do not overload the tires by exceeding the
specified load limit as indicated on the Tire
and Loading Information placard on the
driver's door B-pillar. Overloading the tires
can overheat them, possibly causing a
blowout. Overloading the tires can also result
in handling or steering problems, or brake
failure.
Check the tire pressure at least once a month.
Only check and correct tire pressures when
the tires are cold ( Y page 493).
Checking tire pressure manually
To determine and set the correct tire
pressure, proceed as follows:
XRemove the valve cap of the tire that is to
be checked.XPress the tire pressure gauge securely onto
the valve.XRead the tire pressure and compare it with
the recommended value on the Tire and
Loading Information placard on the
B-pillar on the driver's side of your vehicle.XIf necessary, increase the tire pressure to
the recommended value ( Y page 493).XIf the tire pressure is too high, release air
by pressing down the metal pin in the valve
using the tip of a pen, for example. Thencheck the tire pressure again using the tire
pressure gauge.XScrew the valve cap onto the valve.XRepeat these steps for the other tires.
Tire pressure monitor
Important safety notes
If a tire pressure monitor system is installed,
the vehicle's wheels have sensors that
monitor the tire pressures in all four tires. The
tire pressure monitor warns you when the
pressure drops in one or more of the tires. The
tire pressure monitor only functions if the
correct wheel electronics units are installed
on all wheels.
The tire pressure monitor has a yellow
warning lamp in the instrument cluster for
indicating pressure loss/malfunctions (USA)
or pressure loss (Canada). Whether the
warning lamp flashes or lights up indicates
whether a tire pressure is too low or the tire
pressure monitoring system is
malfunctioning:
R if the warning lamp is lit continuously, the
tire pressure on one or more tires is
significantly too low. The tire pressure
monitor is not malfunctioning.
R USA only: if the warning lamp flashes for
60 seconds and then remains lit constantly,
the tire pressure monitor is malfunctioning.
GWARNING
Each tire, including the spare (if provided),
should be checked at least once a month
when cold and inflated to the pressure
recommended by the vehicle manufacturer
on the Tire and Loading Information placard
on the driver's door B-pillar or the tire
pressure label on the inside of the fuel filler
flap. If your vehicle has tires of a different size
than the size indicated on the Tire and Loading
Information placard or the tire pressure label,
you should determine the proper tire pressure
for those tires.
Tire pressure497Wheels and tiresZ

Kilopascal (kPa)
Metric unit for tire pressure. 6.9 kPa is the
equivalent of 1 psi. Another unit for tire
pressure is bar. There are 100 kilopascals
(kPa) to 1 bar.
Load index
In addition to the load bearing index, the load
index may also be imprinted on the sidewall
of the tire. This specifies the load bearing
capacity more precisely.
Curb weight
The weight of a vehicle with standard
equipment including the maximum capacity
of fuel, oil and coolant. It also includes the air-
conditioning system and optional equipment
if these are installed in the vehicle, but does
not include passengers or luggage.
Maximum load rating
The maximum load rating in kilograms or
pounds is the maximum weight for which a
tire is approved.
Maximum permissible tire pressure
Maximum permissible tire pressure for one
tire.
Maximum load on one tire
Maximum load on one tire. This is calculated
by dividing the maximum axle load of one axle
by two.
PSI (pounds per square inch)
A standard unit of measure for tire pressure.
Aspect ratio
Relationship between tire height and tire
width in percent.
Tire pressure
This is pressure inside the tire applying an
outward force to each square inch of the tire's
surface. The tire pressure is specified in
pounds per square inch (psi), in kilopascal
(kPa) or in bar. The tire pressure should only
be corrected when the tires are cold.
Tire pressure of cold tires
The tires are cold:
R if the vehicle has been parked without
direct sunlight on the tires for at least three
hours and
R if the vehicle has not been driven more than
1 mile (1.6 km).
Tread
The part of the tire that comes into contact
with the road.
Bead
The tire bead ensures that the tire sits
securely on the wheel. There are several steel
wires in the bead to prevent the tire from
coming loose from the wheel rim.
Sidewall
The part of the tire between the tread and the
bead.
Weight of optional extras
The combined weight of those optional extras
that weigh more than the replaced standard
part and more than 2.3 kilograms (5 lbs).
512Definition of terms for tires and loadingWheels and tires