2007 MERCEDES-BENZ GL450 check engine light

351 Operation
Driving instructions
To 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.
Refer to the description of the Brake Assist
System (BAS) (
page 105).Brake pad wear or a leak in the system may
be the reason for low brake fluid in the
reservoir.
The brake fluid level in the reservoir may
be too low if the brake warning lamp in the
instrument cluster comes on and an
acoustic warning sounds although the
parking brake is released (
page 437).
Observe additional messages in the multi-
function display that may appear
(
page 472).
Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Light Truck Center.
All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
Mercedes-Benz Light Truck Center.
Only install brake pads and brake fluid
recommended by Mercedes-Benz.
After hard braking, it is advisable to drive
on for some time, rather than immediately
park, so that the air stream will cool down
the brakes faster.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Warning!G
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired. This
could result in an accident.
!When driving down long and steep grades,
relieve the load on the brakes by shifting into a
lower gear to use the engine’s braking power.
This helps prevent overheating of the brakes and
reduces brake pad wear.
When using the engine’s braking power, a drive
wheel may not spin for an extended period of
time, e.g. on slippery road surfaces. This may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.

365 Operation
Driving instructions
Returning from off-road drivingOff-road driving increases strain on the
vehicle.
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 off the off-road driving program
(
page 280) or the LOW RANGE
mode* (
page 203).

Switch off the DSR (page 276).

Set the differential locks* to AUTO
(
page 207).

Lower the vehicle back to a level
suitable for road conditions, e.g. High-
way/High-speed level (
page 281).

Clean all exterior lamps and check for
possible damage.

Clean the front and rear license plate.

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.

Check tires for possible damage.

Inspect vehicle underbody, oil pan,
brake hoses, etc., as well as vehicle un-
derbody for possible damage.

Check for brush or branches caught in
the underbody.

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.
Warning!G
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 may influence driving
comfort and pose the risk of accident to you
and other drivers.
!Brush or branches could increase the possi-
bility of a fire, as well as cut fuel and/or brake
lines, puncture rubber bellows of the axles or
drive shafts.

368 Operation
Driving instructions
Attaching a trailerObserve maximum permitted trailer
dimensions (width and length).
Most states and all Canadian provinces
require

safety chains between your tow vehicle
and the trailer.
The chains should be criss-crossed
under the trailer tongue. They must be
attached to the hitch receiver, and not
to the vehicle’s bumper or axle.
Ma ke sur e to l ea ve e nough s la ck i n the
chains to permit turning corners.

a separate brake system at various
trailer weights.

a break-away switch on trailers with a
separate brake system. Check with
your local state laws for specific
requirements.
The switch activates the trailer brakes
in the possible event that the trailer
might separate from the tow vehicle.
Make sure the automatic transmission
is set toP (
page 194).
Set the parking brake for the vehicle
(
page 68).
Start the engine (page 57).
Set the vehicle level to Highway
(
page 281).
Vehicle with ADS*: Set the ADS* to
AUTO or COMFORT (
page 280).
Turn off the engine (page 69).
Warning!G
While you are coupling or decoupling a trail-
er, make sure that you do not

lock or unlock

open or close
a vehicle door or the tailgate.
The vehicle’s level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
button* (
page 281) or the vehicle level
control system (
page 281) when cou-
pling/decoupling the trailer.
!Do not connect a trailer brake system (if
trailer is so equipped) directly to the vehicle’s
hydraulic brake system, as your vehicle is
equipped with antilock brakes. If you do, neither
the vehicle’s brakes nor the trailer’s brakes will
function properly.
iThe provided vehicle electrical connector for
trailer towing has a brake signal wire for hook-up
to a brake controller.
You should consider using a trailer sway control
system. For further information, contact an
authorized Mercedes-Benz Light Truck Center.

380 Operation
Engine compartment
The hood lock release lever is located in
the driver’s footwell.
1Release lever
Pull release lever1 downwards.
The hood is unlocked. Handle2 pro-
trudes slightly from the radiator grille.
If not, lift the hood slightly.2Handle for opening the hood
Press and hold handle2.
The hood is unlocked.
Pull up on the hood in direction of ar-
row and then release it.
The hood will be automatically held
open at shoulder height by gas-filled
struts.ClosingLet the hood drop from a height of
approximately 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.

with the engine running

while starting the engine

when the ignition is switched on
!To avoid damage to the windshield wipers or
hood, never open the hood if the wiper arms are
folded forward away from the windshield.
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 others.


381 Operation
Engine compartment
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Increased oil consumption
can occur when

the vehicle is new

the vehicle is driven frequently at
higher engine speeds
Engine oil consumption checks should only
be made after the vehicle break-in period.Checking engine oil level with the oil
dipstick
When checking the oil level

the vehicle must be parked on level
ground

the vehicle must have been stationary
for at least 5 minutes with the engine
turned off
Example GL 450 (GL 320 CDI similar)
1Oil dipstick
2Upper mark
3Lower mark
Open the hood (page 379).
Pull out oil dipstick1.
Wipe oil dipstick1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
Pull out oil dipstick1 again after
approximately 3 seconds to obtain
accurate reading.
The oil level is correct when it is be-
tween lower mark3 (min.) and upper
mark2 (max.) of the oil dipstick.
If necessary, add engine oil
(
page 382).
For more information on engine oil, see
“Technical data” section (
page 560) and
(
page 562).
iDo not use any special lubricant additives,
as these may damage the drive assemblies.
Using special additives not approved by
Mercedes-Benz may cause damage not covered
by the Mercedes-Benz Limited Warranty.
More information on this subject is available at
any Mercedes-Benz Light Truck Center.
iThe filling quantity between the upper and
lower marks on the oil dipstick is approximately
2.1 US qt. (2.0 l).

382 Operation
Engine compartment
Adding engine oil
Example GL 450 (GL 320 CDI similar)
1Filler cap
Unscrew filler cap1 from filler neck.
Add engine oil as required. Never over-
fill with oil.
Be careful not to spill any oil when adding.
Avoid environmental damage caused by oil
entering the ground or water.
Screw filler cap1 back on filler neck.
For more information on engine oil, see
“Technical data” section (
page 560) and
(
page 562).
Transmission fluid level
The transmission fluid level does not need
to be checked. If you notice transmission
fluid loss or gear shifting malfunctions,
have an authorized Mercedes-Benz Light
Truck Center check the automatic trans-
mission.
Coolant level
The engine coolant is a mixture of water
and anticorrosion/antifreeze. To check the
coolant level, the vehicle must be parked
on level ground.
!Only use approved engine oils and oil filters
required for vehicles with Maintenance System.
For a listing of approved engine oils and oil
filters, refer to the Factory Approved Service
Products pamphlet (USA only) in your vehicle
literature portfolio, or contact an authorized
Mercedes-Benz Light Truck Center.
Using engine oils and oil filters of specification
other than those expressly required for the
Maintenance System, or changing of oil and oil
filter at change intervals longer than those called
for by the Maintenance System will result in
engine or emission control system damage not
covered by the Mercedes-Benz Limited
Warranty.
!Excess oil must be siphoned or drained off.
It could cause damage to the engine and/or
catalytic converter (gasoline engine) or the oxi-
dation catalyst (diesel engine) not covered by
the Mercedes-Benz Limited Warranty.

420 Operation
Winter driving
Before the onset of winter, have your
vehicle winterized at an authorized
Mercedes-Benz Light Truck Center. This
service includes:

Check of anticorrosion and antifreeze
concentration.

Addition of cleaning concentrate to the
water of the windshield and headlamp
cleaning system. Add MB Concentrate
“MB SummerFit” to a premixed wind-
shield washer solvent/antifreeze
which is formulated for below freezing
temperatures (
page 567).

Battery test. Battery capacity drops
with decreasing ambient temperature.
A well charged battery helps to make
sure that the engine can be started
even at low ambient temperatures.

Tire change. Mercedes-Benz recom-
mends M+S rated radial-ply tires with a
minimum tread depth of approximately
1/6in (4 mm) on all four wheels for the
winter season.
Winter tires
Always use winter tires at temperatures
below 45°F (7°C) and whenever wintry
road conditions prevail. Not all M+S rated
tires provide special winter performance.
Make sure the tires you use show the
mountain/snowflake.marking on the
tire sidewall. These tires meet specific
snow traction performance requirements
of the Rubber Manufacturers Association
(RMA) and The Rubber Association of Can-
ada (RAC) and have been designed specif-
ically for use in snow conditions. Use of
winter tires is the only way to achieve the
maximum effectiveness of the ABS, ESP
®,
4-ETS, and EBP in winter operation.
For safe handling, make sure all mounted
winter tires are of the same make and have
the same tread design.Always observe the speed rating of the
winter tires installed on your vehicle. If the
maximum speed for which your tires are
rated is below the speed rating of your
vehicle, you must place a notice to this
effect where it will be seen by the driver.
Such notices are available from your tire
dealer or from any authorized
Mercedes-Benz Light Truck Center.
Warning!G
Winter tires with a tread depth of less than 1/6in (4 mm) must be replaced. They are no
longer suitable for winter operation.

424 Operation
Maintenance
Calling up the maintenance service
indicator display
You can call up the maintenance service in-
dicator display at any time to check when
the next maintenance service is due.
Switch on the ignition (page 42).
Press buttonè orÿ on the mul-
tifunction steering wheel repeatedly
until the standard display appears in
the multifunction display (
page 164).
Press buttonk orj until the
maintenance service indicator display
with the service symbol9 and the
service deadline appears in the multi-
function display.Resetting the maintenance service
indicator
In the event that the maintenance service
on your vehicle is not carried out by an
authorized Mercedes-Benz Light Truck
Center, you can have the maintenance
service indicator reset. The automotive
maintenance facility carrying out the
maintenance service will find the informa-
tion for resetting the maintenance service
indicator in the maintenance-relevant
information for your vehicle. Such informa-
tion is available from either your
authorized Mercedes-Benz Light Truck
Center or directly from Mercedes-Benz.
iIf the battery is disconnected, the days of
disconnection will not be included in the count
shown by the maintenance service indicator.To arrive at the true maintenance service dead-
line, you will need to subtract these days from
the days shown in the maintenance service indi-
cator message or maintenance service indicator
display.
Do not confuse the maintenance service indica-
tor with the engine oil level indicatorN.
!If the maintenance service indicator was
inadvertently reset, have an authorized
Mercedes-Benz Light Truck Center correct it.
Only reset if the proper maintenance service has
been performed. Resetting the system without
performing the proper service as called for by
the maintenance service indicator will result in
engine damage and/or other vehicle damage not
covered by the Mercedes-Benz Limited
Warranty.