2008 MERCEDES-BENZ S-Class ECU

574 OperationEngine compartment
Closing
Let the hood drop from a height of ap-
proximately 1 ft (30 cm).
The hood will lock audibly.

Check to make sure the hood is fully
closed.
If you can raise the hood at a point
above the headlamps, then it is not
properly closed. Open it again and let it
drop with somewhat greater force.
Warning!
G
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running.
The radiator fan may continue to run for ap-
proximately 30 seconds or even restart af-
ter the engine has been turned off. Stay
clear of fan blades.Warning!
G
If you see flames or smoke coming from the
engine compartment, or if the coolant tem-
perature gauge indicates that the engine is
overheated, do not open the hood. Move
away from vehicle and do not open the hood
until the engine has cooled down. If neces-
sary, call the fire department.
Warning!
G
The engine is equipped with a transistorized
ignition system. Because of the high voltage
it is dangerous to touch any components (ig-
nition coils, spark plug sockets, diagnostic
socket) of the ignition system

with the engine running


while starting the engine


if ignition is “on” and the engine is
cranked manually
Warning!
G
When closing the hood, use extreme caution
not to catch hands or fingers. Be careful that
you do not close the hood on anyone.
Make sure that the hood is securely en-
gaged before driving off. Do not continue
driving if the hood can no longer engage af-
ter an accident, for example. The hood could
otherwise come loose while the vehicle is in
motion and endanger you and/or others.


645 Practical hints
What to do if …?
Display
Possible cause/consequence
Possible solution
Cruise Control
- - - mph
(USA only)
Cruise Control
- - - kmh
(Canada only)
You have tried to switch on
cruise control below a speed of
20 mph (30 km/h).

Drive faster than 20 mph (30 km/h) and save the speed.
ESP
® is switched off.

Switch on ESP
® (page 76).
The automatic transmission is in
park position P, reverse gearR
or neutral positionN.

Shift the automatic transmission to drive positionD (
page 426).
The system is overheated.

Wait until the system cools down.
The vehicle is secured in place
by the electronic parking brake.

Release electronic parking brake (
page 422).
Cruise Control
Inoperative
Cruise control is malfunction-
ing.

Have cruise control checked by an authorized Mercedes-Benz Center.

647 Practical hints
What to do if …?
Display
Possible cause/consequence
Possible solution
DISTRONIC PLUS
Override
You have depressed the accelerator pedal,
DISTRONIC Plus* is no longer controlling
the speed of the vehicle.

Release the accelerator pedal.
DISTRONIC PLUS
- - - mph
(USA only)
Canada only:
DISTRONIC PLUS
- - - kmh
(Canada only)
You have attempted to activate DISTRONIC
Plus* at a speed below 20 mph (30 km/h)
without the vehicle in front being displayed
in the multifunction display (
page 454).

Drive faster than 20 mph (30 km/h) and activate DISTRONIC
Plus* again.
ESP
® is switched off.

Switch on ESP
® (page 76).
The automatic transmission is in park posi-
tion P, reverse gearR or neutral positionN.

Shift the automatic transmission to drive positionD
(page 426).
The system is overheated.

Wait until the system cools down.
The vehicle is secured in place by the elec-
tronic parking brake.

Release electronic parking brake (
page 422).
The driver’s door is open and the drivers
seat belt is unbuckled.

Close the driver’s door and fasten your seat belt.
The hood is open.

Close the hood (
page 574).

651 Practical hints
What to do if …?
Display
Possible cause/consequence
Possible solution
Front Passenger
Airbag Enabled
See Oper. Manual
Front passenger front air bag is
activated while driving even
though a child, small individual,
or object below the system’s
weight threshold is on the front
passenger seat, or the front pas-
senger seat is empty. Objects
on the seat or forces acting on
the seat may make the system
sense supplemental weight.
Stop the vehicle in a safe location as soon as possible and check the front
passenger seat for the following:
Engage the electronic parking brake (
page 422).

Switch off the ignition (
page 370).

Remove child and child restraint from front passenger seat and properly
secure the child in rear seat employing the child restraint if necessary.

Remove any other items from on and around the front passenger seat and
make sure the storage bag on the back of the front passenger seat is emp-
ty.

Make sure that no objects which apply forces to the seat are present (e.g.
objects such as books, briefcases etc. lodged behind or around the seat,
head restraints pushing against roof etc.). The system may recognize such
forces as supplemental weight and sense that an occupant on the front
passenger seat is of a greater weight than actually present.

Keep the seat unoccupied, close the front passenger door and switch on
the ignition (
page 370).
Monitor the 59indicator lamp right of the instrument cluster
(
page 51) and the multifunction display in the instrument cluster
(page 287) for the following:
(Continued on next page)

707 Practical hints
Where will I find ...?
Minispare wheel
The Minispare wheel is stored in the com-
partment underneath the trunk floor.
1Minispare wheel with spare wheel bolts
in container on wheel rim
2Luggage bowl
3Vehicle tool kit, jack and collapsible
wheel chock
Removing the Minispare wheel
Turn luggage bowl2 counterclock-
wise.

Remove Minispare wheel1.Setting up the collapsible wheel chock
The collapsible wheel chock serves to
additionally secure the vehicle, e.g. while
changing the wheel.
1Tilt the plates upward
2Fold the lower plate outward
3Insert the plate

Tilt both plates upward1.

Fold the lower plate outward2.

Guide the tabs of the lower plate all the
way into the openings of the base
plate3.
For information on where to place wheel
chocks when changing a wheel, see “Lift-
ing the vehicle” (
page 724).

730 Practical hintsBatteries!
The consumer battery located in the trunk is
a valve-r
egulated l
ead a
cid (VRLA) battery, also
referred to as “fleece” battery. Such batteries do
not require topping-up of the electrolyte level.
VRLA batteries therefore do not have cell caps
and the battery cover is non-removable. Do not
attempt to open the consumer battery as other-
wise the battery will be damaged.
Even though VRLA batteries do not require top-
ping-up of the electrolyte level and cannot be
opened to check the electrolyte level, the bat-
tery condition must be checked periodically by
performing a battery conductance test. Refer to
Maintenance Booklet for battery condition test-
ing intervals.
As with any other battery, disconnect the con-
sumer battery if you do not intend to operate
your vehicle for an extended period of time to
prevent battery discharge or connect an acces-
sory battery charge unit expressly approved by
Mercedes-Benz for your vehicle model to main-
tain the battery charge. Contact an authorized
Mercedes-Benz Center for further information.
!
The factory-equipped VRLA battery is
leak-proofed. Only use a battery as replacement
that has the same security features and is of
identical size, voltage, and capacity as the facto-
ry-equipped battery.
The battery, the battery ventilation and the later-
al plug must always be securely installed when
the vehicle is in operation.
Warning!
G
Failure to follow these instructions can re-
sult in severe injury or death.
Never lean over batteries while connecting,
you might get injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come in contact with eyes,
skin or clothing. In case it does, immediately
flush affected area with water and seek
medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.Warning!
G
Do not place metal objects on the battery as
this could result in a short circuit.
Use leak-proof battery only to avoid the risk
of acid burns in the event of an accident.
Take care that you do not become statically
charged, e.g. by wearing synthetic clothing
or rubbing against textiles. For this reason,
you also should not pull or push the battery
over carpets or other synthetic materials.
Never touch the battery first. First touch the
outside body of the vehicle in order to re-
lease any possible electrostatic charges.

731 Practical hints
Batteries
Starter battery (example illustration from
S 550)1Negative terminal
2Positive terminal
Disconnecting starter battery
Secure vehicle in place with electronic
parking brake (
page 422).

Shift the automatic transmission to
park positionP (
page 426).
Do not rub the battery with rags or cloths.
The battery could explode if touched due to
electrostatic charge or due to spark forma-
tion.!
Switch off the engine and switch off the ve-
hicle’s internal electrical functions (
page 732)
before you disconnect or remove the battery’s
terminal clamps. You could otherwise destroy
electronic assemblies such as the generator.
Have the battery checked regularly by an autho-
rized Mercedes-Benz Center. Refer to Mainte-
nance Booklet for maintenance intervals or
contact an authorized Mercedes-Benz Center for
further information.
!
Do not connect any consumers directly to
the starter battery. The starter battery will other-
wise be discharged.
i
Only replace a discharged battery with a bat-
tery recommended by Mercedes-Benz. The con-
sumer battery is installed in the trunk in such a
way that it is safeguarded as much as possible
against mechanical destruction in the event of
an accident.
i
Remove SmartKey from starter switch (vehi-
cles with KEYLESS-GO*: Make sure the vehicle’s
on-board electronics have status 0)
(
page 370) when you turn off the engine and
no longer require any electrical consumers. The
vehicle then uses very little power and the con-
sumer battery is spared.
i
If the consumer battery is discharged, you
must use the mechanical key to unlock the vehi-
cle (page 708). Since the vehicle has a sepa-
rate starter battery, however, you can still start
the vehicle.
!
Always disconnect the starter battery in the
order described below. You could otherwise
damage the vehicle’s electronics.
!
Switch off the vehicle’s internal electrical
functions before disconnecting the starter bat-
tery. If the vehicle is stationary for more than one
hour with the SmartKey removed, you do not
need to switch off the vehicle’s internal electrical
functions.

733 Practical hints
Batteries
Starter battery
Connect the switched-off charging de-
vice to the terminals of the starter bat-
tery. Observe the operating
instructions in the manual for the
charging device while doing so.
Reinstalling starter battery
Install starter battery in engine com-
partment.

Swing retaining bar down.
Reconnecting starter battery

Make sure that the consumer battery in
the trunk is correctly installed and con-
nected.

Turn SmartKey in starter switch to po-
sition 0 and remove.

Connect the positive lead and fasten its
cover2 (
page 731).

Connect negative lead1
(page 731).

Attach ventilation tube.

Switch on the ignition (
page 370).

Start the engine (
page 416).

Check vehicle functions.
!
Only use charging devices with a maximum
charging voltage of 14.8 V.
Warning!
G
During the charge procedure, there is a risk
of acid burns due to gases escaping from
the battery. Do not bend over the battery
during the charge procedure.
!
The battery and the battery ventilation hose
must always be securely installed when the vehi-
cle is in operation.
!
Always connect the starter battery in the or-
der described below. Otherwise, the vehicle’s
electronics could be damaged.
Warning!
G
Do not drive without a properly installed and
connected consumer battery.
Have any work on the consumer battery car-
ried out by an authorized Mercedes-Benz
Center.
!
Never invert the terminal connections.
!
Make sure that the battery has a plug where
the ventilation tube is attached to it.