2003 MERCEDES-BENZ G500 check engine

157 Controls in detail
Climate control
Air conditioning
The air conditioning is operational while
the engine is running and cools the interior
air to the temperature set by the operator.
Deactivating
It is possible to deactivate the air condi-
tioning (cooling) function of the climate
control system. The air in the vehicle will
then no longer be cooled or dehumidified.
Press button
°
(page 151).
The indicator lamp on the button
°

lights up.Activating
Moist air can fog up the windows. You can
dehumidify the air with the air conditioner.

Press button
°
again (
page 151).
The indicator lamp on the button
°

goes out.
The air conditioner uses the refrigerant
R134a. This refrigerant is free of CFCs
which are harmful to the ozone layer.Rear passenger compartment adjust-
able air vents
1Air volume control for center air vents
2Left center air vent, adjustable
3Right center air vent, adjustable
iCondensation may drip out from under-
neath the vehicle. This is normal and
not an indication of a malfunction.
!If the
°
button on the climate con-
trol panel starts to blink, this indicates
that the air conditioner is losing refrig-
erant. The compressor has turned itself
off. The air conditioner cannot be
turned on again.


Have the air conditioner checked at
the nearest authorized
Mercedes-Benz Center.

198 OperationDriving instructionsPower assistanceBrakesTo help prevent brake disk corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes.
If your brake system is normally only sub-
jected to moderate loads, you should occa-
sionally test the effectiveness of the
brakes by applying above-normal braking
pressure at higher speeds. This will also
enhance the grip of the brake pads.If the parking brake is released and the
brake warning lamp in the instrument clus-
ter stays on and there is no audible warn-
ing (EBB), the brake fluid level in the
reservoir is too low.
Brake pad wear or a leak in the system may
be the reason for low brake fluid in the res-
ervoir.
Have the brake system inspected at an au-
thorized Mercedes-Benz Light Truck Cen-
ter immediately.
All checks and service work on the brake
system should be carried out by an autho-
rized Mercedes-Benz Light Truck Center.
Install only brake pads and brake fluid
recommended by Mercedes-Benz.Warning!
G
When the engine is not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to stop or steer the vehi-
cle.Warning!
G
After driving in heavy rain for some time
without applying the brakes or through wa-
ter deep enough to wet brake components
or salty road conditions, the first braking ac-
tion may be somewhat reduced and in-
creased pedal pressure may be necessary to
obtain expected braking effect. Maintain a
safe distance from vehicles in front.
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes overheating,
thereby significantly reducing their effec-
tiveness. It may not be possible to stop the
vehicle in sufficient time to avoid an acci-
dent.
!Be very careful not to endanger other
road users when you apply the brakes.
Refer to the description of the Brake
Assist System (BAS) (
page 73).

205 Operation
Driving instructions
Checklist before off-road driving
Engine oil level

Check the engine oil level
(page 218). The display
ENGINE OIL
LEVEL - O.K.
must appear in the mul-
tifunction display.
Only then can the vehicle obtain a trou-
ble-free oil supply, even on steep gradi-
ents.
Tires


Check the tread depth and maintain
specified tire pressure (see tire pres-
sure label inside the fuel filler flap).


Check tires for possible damage and
remove foreign objects.


Replace missing valve caps.Rims


Dented or bent rims can cause tire
pressure loss and damage the tire
beads. For this reason, check and, if
necessary, change rims before driving
off-road.
Vehicle tool kit


Check if the vehicle jack is functional.


In all cases take the vehicle tool kit, a
strong tow rope, a shovel and a small
plank (to put under the vehicle jack on
sandy soil) with you.


Avoid excessive engine
speeds – drive at moderate engine
speeds (max. 3000 RPM).


Before driving through water, deter-
mine its depth.


Do not stop vehicle immersed in
water, and do not shut off the en-
gine.


Maintaining continuous and rea-
sonably vigorous accelerator appli-
cation when driving in sandy soil
will help overcome the vehicle roll-
ing resistance, and help to prevent
the vehicle from sinking into the
ground.


Do not initiate jumps with the vehi-
cle. It interrupts the forward mo-
mentum of the vehicle.


Always drive on slopes with the en-
gine running and the vehicle in
gear.


Inspect the vehicle for possible
damage after each off-road trip.

206 OperationDriving instructionsDriving in steep terrainSlope angle127°
236°

Comply with the warnings
(page 203) and rules for off-road
driving (
page 204).


Driving on embankments, slopes and
other steep inclines should only be
done straight up or downhill, i.e. in the
line of gravity. Maximum vehicle climb-
ing ability is a 80% grade.


Select gear range2 or1 on the auto-
matic transmission (
page 137).


Drive slowly.


Utilize the engine’s braking power
when descending a slope, observe the
engine speed (do not overrev the en-
gine). Apply the service brake as need-
ed.


Check the brakes after a lengthy down-
grade drive.
Traction in steep terrain
Be easy on the accelerator and watch for
continuous wheel traction when driving in
steep terrain.Driving across a hilltop
Decelerate just ahead of a hilltop (do not
select gear rangeN), to prevent the vehi-
cle from speeding up too much after climb-
ing a hill.
Use the momentum of the vehicle to drive
across the hilltop.
After climbing a hill, driving in this manner
prevents the vehicle from:


jumping across the hilltop


loosing its forward momentum.


speeding up too much after climbing
the hill.
iThe 4-ETS helps greatly when starting
out on a steep incline when the front
wheels have then the tendency to slip
due to the weight shifting away the
front axle.The 4-ETS recognizes the sit-
uation and limits the torque for the
front wheels by braking them. Simulta-
neously the torque for the rear wheels
is provided.

210 OperationDriving instructionsOff-road driving increases strain on the ve-
hicle.
We recommend that you inspect the vehi-
cle for possible damage after each off-road
trip. Recognizing any damage and a subse-
quent timely repair reduces the chance of
a possible breakdown or accident later on.
Proceed as follows:

Switch the transfer case in position
HIGH (
page 141).


Disengage differential locks
(page 146).


Remove excessive dirt from tires,
wheels, wheel housings, and under-
body.
For instance, after driving in mud, clean
the radiator, chassis, engine, brakes,
and wheels from extreme dirt using a
strong jet of water.


Inspect frame, oil pan, brake hoses,
etc., as well as vehicle underbody for
possible damage.


Check tires for possible damage and
remove foreign objects. Clean all exte-
rior lamps and conduct a brake test.


Clean all exterior lamps and check
them for possible damage.


Check for brush or branches caught in
the undercarriage.
They could increase the possibility of a
fire, as well as cut fuel and/or brake
lines, puncture rubber bellows of the
axles or drive shafts.


After continued operation in mud,
sand, water or other dirty conditions,
clean the brake discs, wheels, brake
pads and check and clean axle joints.


Conduct a brake test.Control and operation of radio trans-
mitters
COMAND, radio and telephone*Warning!
G
Do not forget that your primary responsibili-
ty is to drive the vehicle safely. Only operate
the COMAND, radio or telephone
1 if road,
traffic and weather conditions permit.
Bear in mind that at a speed of just 30 mph
(approximately 50 km / h), your vehicle is
covering a distance of approximately
50 feet (approximately 14 m) every second.
1Observe all legal requirements.

215 Operation
At the gas station
Check regularly and before a long trip
1Coolant
2Brake fluid
Coolant
For normal replenishing, use water (pota-
ble water quality). For more information on
coolant level see (
page 220) and the
“Technical data” section (
page 316).
Brake fluid
More information on brake fluid can be
found in the “Technical data” section
(
page 316).Windshield/rear window washer sys-
tem and headlamp cleaning system
For more information on refilling the reser-
voir, see (
page 222).
Engine oil level
For more information on engine oil, see
(
page 218).
Vehicle lighting
Check function and cleanliness. More in-
formation on replacing light bulbs can be
found in the “Practical hints” section
(page 279).
Exterior lamp switch (
page 100).
Tire inflation pressure
For more information on tire inflation pres-
sure, see (
page 225).
iUse only premium unleaded gasoline
with a minimum Posted Octane Rating
of 91 (average of 96 RON / 86 MON).
Information on gasoline quality can
normally be found on the fuel pump.
More information on gasoline can be
found in the Factory Approved Service
Products pamphlet. iLeaving the engine running and the fuel
cap open can cause the
?
lamp to
illuminate.
See also “Practical hints” section
(
page 243).
iOpening the hood, see (
page 216).

217 Operation
Engine compartment
Closing
Lower hood and let it drop into lock
from a height of approximately 0.7 ft
(20 cm).
The hood will lock audibly.

Check to make sure that 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.
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Higher oil consumption can
occur when

the vehicle is new


the vehicle is driven frequently at high-
er engine speeds.
Engine oil consumption checks should only
be made after the vehicle break-in period.
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
turned manually
Warning!
G
Be careful that you do not close the hood on
anyone.!Do not push the hood closed manually,
as this could damage it.
iDo not use any special lubricant addi-
tives, as these may damage the drive
assemblies. Using special additives not
approved by Mercedes-Benz will re-
strict your warranty entitlement.
More information on this subject is
available at any Mercedes-Benz Light
Truck Center.

218 OperationEngine compartmentChecking engine oil level
When checking the oil level the vehicle
must

be parked on level ground


be at normal operating temperature


have been stationary for at least five
minutes with the engine turned off
With the operating system
You can check the engine oil level on the
multifunction display.

Turn the key in the starter switch to
position2.
The standard display (
page 111) should
appear in the multifunction display.

Press button
k
or
j
on the
steering wheel until the following mes-
sage is seen in the multifunction dis-
play:
ENGINE OIL LEVEL - MEASUREMENT IN
PROCESS! MEASUREMENT CORRECT ONLY
IF VEH. LEVEL
After about three seconds, this mes-
sage is displayed:
ENGINE OIL LEVEL –
MEASURING NOW!
One of the following messages will sub-
sequently appear in the indicator:

ENGINE OIL LEVEL – OK



ENGINE OIL LEVEL – ADD 1.0 QUART
(1.0 LITER)!


ENGINE OIL LEVEL – ADD 1.5 QUART
(1.5 LITER)!


ENGINE OIL LEVEL – ADD 2.0 QUART
(2.0 LITER)!
Other display messages
If there is excessive engine oil with the en-
gine at normal operating temperature, the
following message will appear: ENGINE OIL LEVEL – REDUCE OIL LEVEL! 
Have excess oil siphoned.
If the key is not turned to position2 in the
starter switch:
ENGINE OIL LEVEL – SWITCH ON IGNITION!
Switch on the ignition.
iIf you want to cancel the measuring
process, press the
k
or
j
but-
tons on the multifunction steering
wheel.
!Excessive oil must be siphoned or
drained off. It could cause damage to
the engine and catalytic converter not
covered by the Mercedes-Benz Limited
Warranty.
The oil dipstick tube allows for draining
of oil by using a suction device
(page 219).