ECU MERCEDES-BENZ G-CLASS SUV 2012 Repair Manual

i
The tyre pressure values given for low
loads are minimum values which offer you
good ride comfor tcharacteristics.
However, you can also use the values given
for higher loads. These are permissible and
will not adversely affect the running of the
vehicle. Checking the tyre pressures
Important safety notes Observe the notes on tyre pressure:
(Y
page 325).
Information on air pressure for the tyres on
your vehicle can be found:
R on the vehicle's tyre and loading informa-
tion table on the B-pillar (Y page 326)
R on the tyre pressure label on the fuel filler
flap (Y page 326)
R in the "Tyre pressure information" section
R in the "Tyre pressure information" section
(Y page 325)
Checking the tyre pressure manually To determine and set the correct tyre pres-
sure, proceed as follows:
X Remove the valve cap of the tyre that is to
be checked.
X Press the tyre pressure gauge securely
onto the valve.
X Read the tyre pressure and compare it with
the recommended value on the tyre and
loading information table on the B-pillar on
the driver's side of your vehicle
(Y page 326).
X The tyre pressure is too low: increase the
tyre pressure to the recommended value.
X The tyre pressure is too high: press down
the metal pin in the valve using the tip of a
pen, for example.
Air is released from the tyre.
X Check the tyre pressure again with the tyre
pressure gauge. X
Screw the valve cap onto the valve.
X Repeatt hese steps for the other tyres. Tyre pressure monitor
Important safety notes It is the driver's responsibility to set the tyre
pressure to the recommended cold tyre pres-
sure suitable for the operating situation
(Y
page 325). Note that the correct tyre pres-
sure for the current operating situation must
first be taught-in to the tyre pressure monitor.
if there is a substantial loss of pressure, the
warning threshold for the warning message is
aligned to the reference values taught-in.
Restart the tyre pressure monitor after
adjusting to the cold tyre pressure
(Y page 328). The current pressures are
saved as new reference values. This will
ensure that a warning message will only
appearift he tyre pressure drops significantly.
The tyre pressure monitor does not warn you
of an incorrectly set tyre pressure. Observe
the notes on the recommended tyre pressure
(Y page 325).
The tyre pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the
tyre is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering manoeuvres.
If a tyre pressure monitor system is fitted, the
vehicle's wheels have sensors fitted that
monitor the tyre pressures in all four tyres.
The tyre pressure monitor warns you when
the pressure drops in one or more of the
tyres. The tyre pressure monitor only func-
tions if the correct sensors are fitted to all
wheels.
Information on tyre pressures is displayed in
the multifunction display. After a few minutes
of driving, the current tyre pressure of each
tyre is shown in the multifunction display.
The tyre pressure values indicated by the on-
board computer may differ from those meas- Tyre pressure
327Wheels and tyres Z

On vehicles that have the same size front and
rear wheels, you can interchange the wheels
every 5000 km to 10,000 km depending on
the degree of tyre wear. Maintain the direc-
tion of tyre rotation.
Cleant he contact surfaces of the wheel and
the brake disc thoroughly every time a wheel
is interchanged. Check the tyre pressure and
reactivate the tyre pressure monitor
(Y page 327) if necessary. Direction of rotation
Tyres with a specified direction of rotation
have additional benefits, e.g. if there is a risk
of aquaplaning. You will only gain these ben-
efits if the correct direction of rotation is
observed.
An arrow on the sidewall of the tyre indicates
its correct direction of rotation.
You may fit the spare wheel against the direc-
tion of rotation. Observe the time restriction
on use as well as the speed limitation speci-
fied on the spare wheel. Storing wheels
Store tyres that are not being used in a cool,
dry and preferably dark place. Protect the
tyres against oil, grease, petrol and diesel. Cleaning the wheels
G
WARNING
Do not use high-pressure cleaners with circu-
lar-jet nozzles (dirt grinders) to clean your
vehicle, in particular the tyres. You could oth-
erwise damage the tyres and cause an acci-
dent. Fitting
awheel
Preparing the vehicle X
Prepare the vehicle as described
(Y page 309).
X If a trailer is coupled to the vehicle, uncou-
ple it.
X Remove the vehicle tool kit and the jack
(Y page 306).
X Secure the vehicle to prevent it from rolling
away.
X Remove the spare wheel from the spare
wheel bracket (Y page 307).
Securing the vehicle against rolling
away X
On level ground: place chocks or other
suitable items unde rthe front and rear of
the wheel that is diagonally opposite the
wheel you wish to change.
X On downhill gradients: place chocks or
other suitable items in front of the wheels
of the front and rear axle.
Raising the vehicle G
WARNING
If you do not position the jack correctly at the
appropriate jacking point of the vehicle, the
jack could tip over with the vehicle raised.
There is a risk of injury.
Only position the jack at the appropriate jack-
ing point of the vehicle. The base of the jack
must be positioned vertically, directly under
the jacking point of the vehicle.
The following must be observed when raising
the vehicle:
R to raise the vehicle, only use the vehicle-
specific jack that has been tested and
approved by Mercedes-Benz. If the jack is
used incorrectly, it could tip over while the
vehicle is raised.
R the jack is designed only to raise and hold
the vehicle for a short time while a wheel 330
Changing
awheelWheels and tyres

is being changed. It is not suited for per-
forming maintenance work under the vehi-
cle.
R avoid changing the wheel on uphill and
downhill slopes.
R before raising the vehicle, secure it from
rolling away by applying the parking brake
and inserting wheel chocks. Neve rdisen-
gage the parking brake while the vehicle is
raised.
R the jack must be placed on a firm, flat and
non-slip surface. On a loose surface, a
large, load-bearing underlay must be used.
On a slippery surface, a non-slip underlay
must be used, e.g. rubber mats.
R do not use wooden blocks or similar
objects as a jac kunderlay. Otherwise, the
jack will not be able to achieve its load-
bearing capacity due to the restricted
height.
R make sure tha tthe distance between the
underside of the tyres and the ground does
not exceed 3 cm.
R never place your hands or feet under the
raised vehicle.
R never lie under the raised vehicle.
R never start the engine when the vehicle is
raised.
R never open or close a door or the tailgate
when the vehicle is raised.
R make sure that no persons are present in
the vehicle when the vehicle is raised. X
Using wheel wrench :, loosen the bolts on
the wheel you wish to change by about one full turn. Do not unscrew the wheel bolts
completely.
Pump lever
;
Notch on pump lever
X Assemble the pump lever for the jack. It can
be found with the vehicle tool kit
(Y page 306). X
Turn pressure release screw =clockwise
as far as it will go using notch ;on the
pump lever.
Pressure release screw =is closed.
i Do not turn pressure release screw =by
more than one to two revolutions. Other-
wise, hydraulic fluid could escape. Changing
awheel
331Wheels and tyres Z

X
Position jack :on the axle carrier
tube ;of the front or rear axle. Jack :
must always stand vertically, even on
slopes.
X Raise the vehicle by pumping in the direc-
tion of the arrow, until the tyre is a maxi-
mum of 3 cm off the ground.
Removing awheel !
Do not place wheel bolts in sand or dirt.
The threads of the wheel bolts and wheel
hubs could otherwise be damaged when
the bolts are tightened.
X Unscrew the wheel bolts.
X Remove the wheel.
Fitting anew wheel G
WARNING
If a wheel hub thread is damaged, do not drive
the vehicle any further .Contactaqualified
specialist workshop. G
WARNING
Only use wheel bolts that have been designed
for the wheel and the vehicle. For safety rea-
sons, Mercedes-Benz recommends that you
only use wheel bolts which have been
approved for Mercedes-Benz vehicles and the
respective wheel. Other wheel bolts could
work loose or damage the brake system.
Do not tighten the wheel bolts completely
while the vehicle is still jacked up. The vehicle
could topple off the jack. Always pay attention to the instructions and
safety notices in "Changing a wheel"
(Y
page 329).
X Clean the wheel and wheel hub contact
surfaces.
X Place the new wheel on the wheel hub and
push it on.
X Tighten the wheel bolts until they are fin-
ger-tight.
Lowering the vehicle G
WARNING
The wheels could work loose if the wheel nuts
and bolts are not tightened to the specified
tightening torque. There is a risk of accident.
Have the tightening torque immediately
checked at a qualified specialist workshop
after a wheel is changed. X
Open the pressure release screw on the
jack using the pump lever (Y page 330) by
approximately one turn.
X Place the jack to one side.
X Tighten the wheel bolts evenly in a cross-
wise pattern in the sequence indicated
(: toA). The tightening torque must be
130 Nm.
X Push the jack piston back in and close the
drain plug.
X Use the bolts to secure the faulty wheel to
the spare wheel bracket (Y page 307).332
Changing
awheelWheels and tyres