ECU MERCEDES-BENZ G-CLASS 2018 Repair Manual

Where will I find...?
Reflective safety jacket
Removing reflective safety jackets
XRemove the reflective warning vests from
card pockets :.
Information on reflective safety jackets
:Maximum number of washes
;Maximum wash temperature
=Do not bleach
?Do not iron
ADo not use a laundry dryer
BDo not dry-clean
CThis is a class 2 jacket
RThe safety jackets only meet the require-
ments defined by the legal standard:
-if the correct size is used
-if the reflective safety jackets are correctly
fastened
RBefore use, ensure that the reflective safety
jackets are clean and intact. The special prop-
erties may otherwise be compromised.
RThe reflective safety jackets should be stored
in their original packaging in a dry place away
from sources of heat and light.
RThe maximum number of washes specified is not the only factor influencing the life span of
the reflective safety jackets. Their life span
also depends on use, care, storage, etc.
RThe reflective safety jackets should be dis-
posed of and replaced with new ones:
-after 15 washes, and/or
-if the reflective strips have become
scratched, and/or
-if the backing material and/or reflective
strips have become soiled and cannot be
cleaned off, and/or
-if the fluorescence has faded, for example
due to the effects of sunlight
RDispose of reflective safety jackets in an envi-
ronmentally responsible manner. To do so,
contact your local waste disposal company.
Warning triangle
Removing the warning triangle
The warning triangle is secured under the rear
bench seat.
XRelease tabs ;.
XRemove warning triangle :.
Where will I find...?243
Breakdown assistance

XPull bar=up and detach from tab ?.
XRemove jack;.
Exterior spare wheel bracket
General notes
When using a spare wheel of a different size, you
must not exceed a maximum permissible speed
of 50 mph (80 km/ h).
If you mount the spare wheel, check the tire
pressure.
iWhen changing a wheel, you should also
observe the safety notes in the "Spare wheel"
section (
Ypage 279).
The spare wheel is on the outer side of the rear
door.
Stainless-steel spare hub cap
XTake the screwdriver out of the vehicle tool kit
(Ypage 244).
XOpen the lock on cover ring :with screw-
driver =or a similar tool.
XFold tab ;down.
XPull cover ring :apart and remove it.
XPull off trim panel ?.
XWhen re-installing cover panel ?, make sure
that retainer Aengages into recess B.
Removing the spare wheel
The spare wheel is heavy. Take particular note of
this when removing the spare wheel.
XRemove wheel nuts:.
XRemove the spare wheel.
Mounting the wheel
After changing a wheel:
XRepair or replace the damaged wheel as soon
as possible and secure the spare wheel in
place again.
XSecure the damaged wheel on the spare
wheel bracket with wheel nuts :. When
doing so, make sure that the wheel cannot
come loose.
XWhen re-installing trim panel ?, make sure
that retainer Bengages in recess A
(
Ypage 245).
Where will I find...?245
Breakdown assistance

XMake sure that tab;is below when re-
installing cover ring :(Ypage 245).
XFor safety reasons, regularly check to ensure
that the wheel is securely fastened.
Flat tire
Preparing the vehicle
Observe the notes on changing a wheel
(Ypage 275).
XStop the vehicle on solid, non-slippery and
level ground, as far away as possible from
traffic.
XSwitch on the hazard warning lamps.
XSecure the vehicle against rolling away
(Ypage 122).
XIf possible, bring the front wheels into the
straight-ahead position.
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
The steering wheel lock stays active for as
long as the SmartKey is removed.
XMake sure that the passengers are not endan-
gered as they do so. Make sure that no one is
near the danger area while a wheel is being
changed. Anyone who is not directly assisting
in the wheel change should, for example,
stand behind the barrier.
XGet out of the vehicle. Pay attention to traffic
conditions when doing so.
XClose the driver's door.
XPlace the warning triangle a suitable distance
away (Ypage 243). Observe legal require-
ments.
Battery (vehicle)
Important safety notes
Special tools and expert knowledge are required
when working on the battery, e.g. removal and
installation. You should therefore have all work
involving the battery carried out at a qualified
specialist workshop.
GWARNING
Work carried out incorrectly on the battery
can lead, for example, to a short circuit and
thus damage the vehicle electronics. This can
lead to function restrictions applying to
safety-relevant systems, e.g. the lighting sys-
tem, the ABS (anti-lock braking system) or the
ESP
®(Electronic Stability Program). The oper-
ating safety of your vehicle may be restricted.
You could lose control of the vehicle, for
example:
Rwhen braking
Rin the event of abrupt steering maneuvers
and/or when the vehicle's speed is not
adapted to the road conditions
There is a risk of an accident.
In the event of a short circuit or a similar inci- dent, contact a qualified specialist workshop
immediately. Do not drive any further. You
should have all work involving the battery car-
ried out at a qualified specialist workshop.
For further information about ABS and ESP
®,
see (Ypage 58) and (Ypage 59).
GWARNING
Electrostatic build-up can lead to the creation of sparks, which could ignite the highly explo-
sive gases of a battery. There is a risk of an
explosion.
Before handling the battery, touch the vehicle
body to remove any existing electrostatic
build-up.
The highly flammable gas mixture forms when
charging the battery as well as when jump-start-
ing.
Always make sure that neither you nor the bat-
tery is electrostatically charged. A build-up of
electrostatic charge can be caused, for exam-
ple:
Rby wearing clothing made from synthetic
fibers
Rdue to friction between clothing and seats
Rif you push or pull the battery across the car-
pet or other synthetic materials
Rif you rub the battery with a cloth
GWARNING
During the charging process, a battery produ-
ces hydrogen gas. If a short circuit occurs or
246Battery (vehicle)
Breakdown assistance

sparks are created, the hydrogen gas can
ignite. There is a risk of an explosion.
RMake sure that the positive terminal of a
connected battery does not come into con-
tact with vehicle parts.
RNever place metal objects or tools on a bat-tery.
RIt is important that you observe the descri-
bed order of the battery terminals when
connecting and disconnecting a battery.
RWhen jump-starting, make sure that the
battery poles with identical polarity are
connected.
RIt is particularly important to observe the
described order when connecting and dis-
connecting the jumper cables.
RNever connect or disconnect the battery
terminals while the engine is running.
GWARNING
Battery acid is caustic. There is a risk of injury.
Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean over
the battery. Keep children away from batter-
ies. Wash away battery acid immediately with
plenty of clean water and seek medical atten-
tion.
HEnvironmental note
Batteries contain dangerous
substances. It is against the
law to dispose of them with
the household rubbish. They
must be collected separately and recycled to protect the
environment.
Dispose of batteries in an
environmentally friendly
manner. Take discharged
batteries to a qualified spe-
cialist workshop or a special
collection point for used bat-
teries.
!Have the battery checked regularly at a
qualified specialist workshop. Observe the service intervals in the Mainte-
nance Booklet or contact a qualified specialist
workshop for more information.
!Always have work on batteries carried out at
a qualified specialist workshop.
Should it, in exceptional circumstances, be
absolutely necessary to disconnect the 12-
volt battery yourself, please observe the fol-
lowing:
RSecure the vehicle to prevent it from rolling
away.
RSwitch off the ignition.
RDisconnect the negative terminal first and
then the positive terminal.
The transmission is locked in position j
after disconnecting the battery.
After the work has been done, install the bat- tery and replace the cover of the positive ter-
minal clamp firmly.
Comply with safety precautions and take pro-
tective measures when handling batteries.
Risk of explosion.
Fire, open flames and smoking are
prohibited when handling the bat-
tery. Avoid creating sparks.
Battery acid is caustic.
Avoid contact with skin, eyes or
clothing.
Wear eye protection.
Keep children away.
Observe this Operator's Manual.
For safety reasons, Mercedes-Benz recom-
mends that you only use batteries which have
been tested and approved for your vehicle by
Mercedes-Benz. These batteries provide
increased impact protection to prevent vehicle
occupants from suffering acid burns should the
battery be damaged in the event of an accident.
Battery (vehicle)247
Breakdown assistance
Z

!Only secure the tow cable or tow bar to the
towing eyes. You could otherwise damage the
vehicle.
!Do not tow with sling-type equipment. This
could damage the vehicle.
!Do not use the towing eye for recovery. This
could damage the vehicle. If in doubt, have
the vehicle recovered using a crane.
!When towing, pull away slowly and
smoothly. If the tractive power is too high, the
vehicles could be damaged.
!Your vehicles is equipped with an automatic
transmission. Therefore, you must not have
the vehicle tow-started. The transmission
may otherwise be damaged.
It is better to have the vehicle transported than
to have it towed away.
If the transfer case can be shifted into the Neu-
tral position, you can tow away the vehicle.
If the transfer case cannot be shifted into the
Neutral position, you can tow away the vehicle
with one axle raised. Please bear the following in
mind:
Rremove the propeller shaft between the trans-
fer case and the rolling axle
Rturn the SmartKey to position 1in the igni-
tion lock
The battery must be connected and charged.
Otherwise, you:
Rcannot turn the SmartKey to position 2in
the ignition lock
Rcannot shift the automatic transmission to
position i
Disarm the automatic locking feature before the vehicle is towed (
Ypage 67). You could other-
wise be locked out when pushing or towing the
vehicle.
Towing eyes
Towing eyes, front
:Towing eyes, front
Towing eye, rear
Rear towing eye :is located under the bumper,
on the left-hand side when viewed in the direc-
tion of travel.
Towing a vehicle with both axles on
the ground
It is important that you observe the safety
instructions when towing away your vehicle
(
Ypage 251).
The automatic transmission automatically shifts
to position jwhen you open the driver's or
front-passenger door or when you remove the
SmartKey from the ignition lock. In order to
ensure that the automatic transmission stays in
position iwhen towing away the vehicle, you
must observe the following points:
XMake sure that the vehicle is stationary.
XTurn the SmartKey to position 2in the igni-
tion lock.
252Towing and tow-starting
Breakdown assistance

XWhen the vehicle is stationary, depress the
brake pedal and keep it depressed.
XShift the transfer case to positionNeutral
(Ypage 150).
XShift the automatic transmission to position
i.
XLeave the SmartKey in position 2in the igni-
tion lock.
XRelease the brake pedal.
XRelease the parking brake.
XSwitch on the hazard warning lamps
(Ypage 88).
In order to signal a change of direction when
towing the vehicle with the hazard warning
lamps switched on, use the combination switch
as usual. In this case, only the indicator lamps
for the direction of travel flash. After resetting
the combination switch, the hazard warning
lamp starts flashing again.
iThe automatic transmission can only
change gear when the battery has sufficient
charge.
If you cannot shift the automatic transmission
to position i, the propeller shafts to the
driven axles must be removed.
Transporting the vehicle
!When the vehicle is loaded for transport, the
front and rear axles must be stationary and on the same transportation vehicle. Positioning
over the connection point of the transport
vehicle is not permitted. The drive train may
otherwise be damaged.
!You may only secure the vehicle by the
wheels, not by parts of the vehicle such as
axle or steering components. Otherwise, the
vehicle could be damaged. The towing eyes can be used to pull the vehicle
onto a trailer or transporter if you wish to trans-
port it.
XTurn the SmartKey to position 2in the igni-
tion lock.
XShift the transfer case to position Neutral
(Ypage 150).
XShift the automatic transmission to position
i.
As soon as the vehicle has been loaded:
XApply the parking brake.
XShift the automatic transmission to position
j.
XTurn the SmartKey to position gin the igni-
tion lock and remove it.
XSecure the vehicle.
Recovering a vehicle that has become
stuck
!
When recovering a vehicle that has become
stuck, pull it as smoothly and evenly as pos-
sible. Excessive tractive power could damage
the vehicles.
If the drive wheels have become stuck in loose
or muddy ground, pull the vehicle out with
extreme caution, especially so if the vehicle is
loaded.
Never attempt to recover a stuck vehicle with a
trailer attached.
Pull out the vehicle backwards, if possible using the tracks it made when it became stuck.
Towing in the event of malfunctions
General notes
!If you are removing the propeller shaft, use
M10 nuts as spacers on the M8 bolts and
secure them with M8 nuts.
New self-locking nuts must be used when the
propeller shafts are refitted.
It is important that you observe the safety
instructions when towing away your vehicle
(
Ypage 251).
iConsult an authorized Mercedes-Benz Cen-
ter.
Towing and tow-starting253
Breakdown assistance
Z

In the event of damage to the engine,
transmission or electrical system
XShift thetransfer cas eto neutra l
(Ypage 150).
XShift th eautomatic transmission to position
i.
In the event of damage to the transfer
case
Hav eth epropelle rshafts between th eaxles and
th etransfer cas eremoved.
In the event of damage to the front axle
Hav eth epropelle rshaf tbetween th erear axl e
and th etransfer cas eremoved.
Then hav eth evehicl etowed away wit hth efron t
axl eraised.
In the event of damage to the rear axle
Hav eth epropelle rshaf tbetween th efron taxl e
and th etransfer cas eremoved.
Then hav eth evehicl etowed wit hth erear axl e
raised and whee lroller sunder th efron taxle.
Tow-starting (emergency engine
starting)
!
Vehicles wit hautomatic transmission must
no tbe tow-started. You could otherwise dam-
age th eautomatic transmission .
You can fin dinformation on "Jump-starting "
under (
Ypage 249).
Fuses
Important safety notes
GWARNIN G
If you manipulat eor bridge afault yfus eor if
you replace it wit h afusewit h a higher amper-
age, th eelectric cables could be overloaded.
This could result in afire. Ther eis aris kof an
acciden tand injury.
Always replace fault yfuses wit hth especifie d
ne wfuses having th ecorrec tamperage .The fuses in your vehicl
eserve to close down
fault ycircuits. If afus eblows ,all th ecompo -
nent son th ecircuit and their function sstop
operating .
Blown fuses must be replace dwit hfuses of th e
sam erating ,whic hyou can recogniz eby th e
color and value .The fus erating sare listed in th e
fus eallocation chart (
Ypage 255).
If anewly inserted fus ealso blows ,hav eth e
caus etrace dand rectifie dat aqualified special-
ist workshop, e.g. an authorize dMercedes-Ben z
Center.
!Only use fuses that hav ebeen approve dfor
Mercedes-Ben zvehicles and whic hhav eth e
correc tfus erating for th esystem concerned.
Otherwise, component sor systems could be
damaged.
!Mak esur ethat no moisture can ente rth e
fus ebox when th ecover is open .
!When closingth ecover ,mak esur ethat it is
lyin gcorrectl yon th efus ebox .Moistur eseep -
ing in or dirt could oth
erwise impair th
eoper -
ation of th efuses.
Before changing a fuse
Pay attention to th eimportant safet ynote s
(Ypage 254).
XSwitc hoff th eengine.
XSwitc hoff all electrical consumers.
XRemove th eSmartKey from th eignition lock.
All indicator lamp sin th einstrumen tcluste r
must be off .
XSecureth evehicl eagainst rollin gaway
(Ypage 122).
The fuses are locate din various fus eboxes:
RMain fus ebox on th efront-passenger side of
th edashboar d
RFusebox in th efront-passenger footwell
RFus ebox in th etransmission tunne l
RFusebox in th ecargo compartmen t
The fus eallocation chart and th espar efuses are
in th efus ebox on th edashboar don th efront-
passenger side (
Ypage 255).
The fus eextractor is in th evehicl etool kit
(
Ypage 244).
254Fuses
Breakdown assistance

Dashboardfuse box
!
Do no tuse apointe dobjec tsuc has ascrew -
driver to ope nth ecover in th edashboard. You
could damage th edashboar dor th ecover .
XOpenth efront-passenger door.
XTo open: pull cover :out in th edirection of
th earrow and remov eit.
XTo close :clip in cover :on th efron tof th e
dashboard.
XFold cover :in until it engages.
Fus ebox in th efront-passenger foot -
well
XUnscrew screw s:.
XLif tup cover ;in th edirection of th earrow.
=Fus ebox
Fus ebox in th etransmission tunnel
XFold th ecup holder on th ecenter console
down (Ypage 215).
XMoveth efront-passenger seat as far forwar d
as possible (Ypage 76).
XTo open: unscrew screw s:.
XRemov ecover ;in th edirection of th e
arrow.
XTo close :clip in cover ;.
XInstall cover ;withscrew s:.
Fuses255
Breakdown assistance
Z

Important safety notes
GWARNING
If wheels and tires of th ewrong siz eare used,
th ewhee lbrakes or suspension component s
may be damaged. Ther eis aris kof an acci-
dent.
Always replace wheels and tires wit hthose
that fulfill th especification sof th eoriginal
part .
When replacing wheels, mak esur eto use th e
correct:
Rdesignation
Rmodel
When replacing tires ,mak esur eto use th e
correct:
Rdesignation
Rmanufacturer
Rmodel
GWarning
A flat tire severely impairs th edriving ,steer -
ing and braking characteristics of th evehicle.
Ther eis aris kof an accident.
do no tdriv ewit h a flat tire. Immediately
replace th eflat tire wit hyour spar ewheel, or
consult aqualified specialist workshop.
Accessories that are no tapprove dfor your vehi-
cle by Mercedes-Ben zor are no tbein gused cor-
rectl ycan impair th eoperating safety.
Before purchasing and usin gnon-approve d
accessories, visit aqualified specialist work-
sho pand ask about :
Rsuitability
Rlegal stipulation s
Rfactory recommendation s
Further information regarding wheels and tires
can be foun dunder "Wheel/tire combinations"
(
Ypage 279).
You can ask for information regarding permitte d
wheel/tire combination sat an authorize d
Mercedes-Ben zCenter. Information on tire pressur
ecan be found:
Ron th eTir eand Loading Information placard
on th eB-pillar on th edriver' sside
(
Ypage 266)
Rin th etire pressur etable in th efuel filler flap
(Ypage 120)
Runder "Tir epressure" (Ypage 260)
Operation
Information on driving
Checkth etire pressur ewhen th evehicl eis
heavily laden and adjust prio rto atrip.
While driving ,pay attention to vibrations, noises
and unusual handlin gcharacteristics ,e.g. pull-
ing to on eside .This may indicat ethat th e
wheels or tires are damaged. If you suspec tthat
a tire is defective, reduce your spee dimmedi-
ately. Stop th evehicl eas soo nas possible to
chec kth ewheels and tires for damage. Hidden
tire damag ecould also be causing th eunusual
handlin gcharacteristics .If you fin dno sign sof
damage, hav eth etires and wheels checke dat a
qualified specialist workshop.
When parking your vehicle, mak esur ethat th e
tires do no tget deformed by th ecur bor other
obstacles. If they canno tbe avoided, driv eove r
obstacles suc has curbs slowly and at an obtuse
angle. You could otherwise damag eth ewhee l
rim sand tires .
Regular checking of wheels and tires
GWARNIN G
Damaged tires can caus etire inflation pres-
sur eloss .As aresult ,you could lose control of
your vehicle. Ther eis aris kof accident.
Chec kth etires regularly for sign sof damag e
and replace any damaged tires immediately.
Chec kwheels and tires for damag eat least once
a month .Chec kwheels and tires after driving
off-road or on roug hroads. Damaged wheels
can caus e aloss of tire pressure.
Pay particular attention to damag esuc has:
Rcut sin th etires
Rpunctures in th etires
Rtears in th etires
Operation257
Wheels and tires
Z

Checking the tire pressures
Important safety notes
Observe the notes on tire pressure
(Ypage 260).
Information on air pressure for the tires on your
vehicle can be found:
Ron the vehicle's Tire and Loading Information
placard on the B-pillar
Rin the tire pressure table in the fuel filler flap
(Ypage 120)
Runder "Tire pressure" (Ypage 260)
Checking tire pressures 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 gage securely onto the
valve.
XRead the tire pressure and compare it to the
recommended value on the Tire and Loading
Information placard or the tire pressure table
(
Ypage 260).
XIf the tire pressure is too low, increase the tire
pressure to the recommended value.
XIf the tire pressure is too high, release air. To
do so, press down the metal pin in the valve,
using the tip of a pen for example. Then check
the tire pressure again using the tire pressure
checker.
XScrew the valve cap onto the valve.
XRepeat these steps for the other tires.
Tire pressure monitor
General notes
If a tire pressure monitor is installed, the vehi-
cle's wheels have sensors that monitor the tire
pressures in all four tires. The tire pressure mon-
itor warns you if the pressure drops in one or
more of the tires. The tire pressure monitor only
functions if the corresponding sensors are
installed in all wheels.
Information on tire pressures is displayed in the
multifunction display. After a few minutes of
driving, the current tire pressure of each wheel
is shown in the Serv.
menu.
Information on the message display can be
found in the "Checking the tire pressure elec-
tronically" section (
Ypage 264).
Important safety notes
GWARNING
Each tire, including the spare (if provided),
should be checked at least once a month
when cold and inflated to the pressure rec-
ommended 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 Infor-
mation placard or the tire pressure label, you
should determine the proper tire pressure for
those tires.
As an added safety feature, your vehicle has
been equipped with a tire pressure monitoring
system (TPMS) that illuminates a low tire pres-
sure telltale when one or more of your tires
are significantly underinflated. Accordingly,
when the low tire pressure telltale illuminates,
you should stop and check your tires as soon
as possible, and inflate them to the proper
pressure. Driving on a significantly underin-
flated tire causes the tire to overheat and can lead to tire failure. Underinflation also
reduces fuel efficiency and tire tread life, and
may affect the vehicle's handling and stop-
ping ability.
Please note that the TPMS is not a substitute
for proper tire maintenance, and it is the driv-
er's responsibility to maintain correct tire
pressure, even if unde rinf
lation has not
reached the level to trigger illumination of the
TPMS low tire pressure telltale.
USA only:
Tire pressure263
Wheels and tires
Z