2004 MERCEDES-BENZ G500 check engine

208 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 immedi-
ately. Contact an authorized
Mercedes-Benz Light Truck Center.
All checks and service work on the brake
system should be carried out by by quali-
fied technicians only. Contact an autho-
rized Mercedes-Benz Light Truck Center.
Install only brake pads and brake fluid
recommended by Mercedes-Benz.Warning!
G
With the engine 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 brake and steer the ve-
hicle.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 76).

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

Check the engine oil level
(page 229). The display
ENGINE OIL
LEVEL - OK
must appear in the multi-
function 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.
iWhenever driving in off-road mode, we
recommend:

Keeping doors, tailgate, windows
and sliding/pop-up roof closed.


Switching cruise control off.
!Observe the following during off-road
driving:

Adjust vehicle speed to condition of
terrain. The more uneven, rutty and
steeper the terrain, the lower the
speed should be. Drive through wa-
ter slowly at an even speed, avoid-
ing a bow wave.


Be especially careful when driving
in unknown territory. It may be nec-
essary to get out of the vehicle and
scout the path you intend to take.


Watch out for obstacles, such as
rocks, holes, tree stumps and ruts.


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


Before driving through water, deter-
mine its depth.


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


In sandy soil, drive at a steady
speed as allowed by conditions.
This helps overcome the vehicle
rolling resistance and reduces the
likelihood of the vehicle 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.

216 OperationDriving instructionsRims

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.Driving in steep terrain
Slope angle127°
236°

Comply with the warnings
(page 214) and rules for off-road
driving (
page 214).


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 142).


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.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.

218 OperationDriving instructions

Comply with the warnings
(page 214) and rules for off-road
driving (
page 214).


Switch off the exterior lamps as well as
the climate control.


Select gear range2 or1 on the auto-
matic transmission (
page 142).


Enter the water only at a shallow spot,
driving at walking speed.


Do not stop vehicle while immersed in
water, and do not shut off the engine.
There is a very high level of driving re-
sistance in water. The surface is slip-
pery and may not be firm, making
pulling away in water difficult and dan-
gerous.


Clean mud off the tire tread after driv-
ing through water.


To dry the brakes, apply pressure to the
brake pedal several times after leaving
the water.
Crossing obstacles
!Never accelerate before driving into
the water. The bow wave could force
water into the engine and auxiliary
equipment, thus damaging them.
!If possible, use the assistance of a sec-
ond person outside the vehicle to scout
the path you intend to take and check
for adequate ground clearance when
you cross obstacles with your vehicle.
The person assisting you outside the
vehicle should always be a safe dis-
tance away from the vehicle and posi-
tioned so that he or she cannot get hurt
in case of any unexpected vehicle
movement.
After off-road driving or crossing obsta-
cles, inspect vehicle for any damage,
especially vehicle undercarriage and
suspension components. Failure to do
so can adversely affect the vehicle’s fu-
ture performance, including increased
chance of an accident.

220 OperationDriving instructionsReturning from off-road drivingOff-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 145).


Disengage differential locks
(page 151).


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.
Warning!
G
Never drive on pavement with activated dif-
ferential locks. Engaged front axle differen-
tial locks limits ability to move around
curves.
If you feel a sudden significant vibration or
ride disturbance, or you suspect that possi-
ble damage to your vehicle has occurred,
you should turn on the hazard warning flash-
ers, carefully slow down, and drive with cau-
tion to an area which is a safe distance from
the roadway.
Inspect the tires and under the vehicle for
possible damage. If the vehicle or tires ap-
pear unsafe, have it towed to the nearest
Mercedes-Benz Light Truck Center or tire
dealer for repairs.
Damage to the vehicle negatively influences
driving comfort and poses the risk of acci-
dent to you and other drivers.

221 Operation
Driving instructions


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*Telephones and two-way radios
Radio transmitters, such as a portable tele-
phone or citizens band unit should only be
used inside the vehicle if they are connect-
ed to an antenna that is installed on the
outside of the vehicle.
Refer to the radio transmitter operation in-
structions regarding use of an external an-
tenna.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.
Warning!
G
Never operate radio transmitters equipped
with a built-in or attached antenna (i.e. with-
out being connected to an external antenna)
from inside the vehicle while the engine is
running. Doing so could lead to a malfunc-
tion of the vehicle’s electronic system, pos-
sibly resulting in an accident and/or
personal injury.

225 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,
see “Coolant level” (
page 232) and see
“Fuels, coolants, lubricants, etc.”
(
page 333).Brake fluid
Windshield/rear window washer sys-
tem and headlamp cleaning system
For more information on refilling the reser-
voir, see “Windshield/rear window washer
system and headlamp cleaning system”
(
page 234).
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 ? malfunc-
tion indicator lamp to illuminate.
See also “Practical hints” section
(page 256).
iOpening the hood, see (
page 227).
!If you find that the brake fluid in the
brake fluid reservoir has fallen to the
minimum mark or below, have the
brake system checked for brake pad
thickness and leaks immediately. Noti-
fy an authorized Mercedes-Benz Light
Truck Center immediately. Do not add
brake fluid as this will not solve the
problem. For more information, see
“Practical hints” (
page 254) .

226 OperationAt the gas stationEngine oil level
For more information on engine oil, see
(page 228).
Vehicle lighting
Check function and cleanliness. For infor-
mation on replacing light bulbs, see “Re-
placing bulbs” (
page 295).
For more information, see “Exterior lamp
switch” (
page 104).
Tire inflation pressure
For more information, see “Checking tire
inflation pressure” (
page 237).