check engine light MERCEDES-BENZ GL320CDI 2007 X164 Owner's Guide

469 Practical hints
What to do if …
Symbol messages
Display symbolDisplay messagesPossible cause/consequencePossible solution
#The battery is no longer charging.
Possible causes:

alternator malfunctioning

broken poly-V-belt
Do not forget that the brake system
requires electrical energy and may be
operating with restricted capability.
Considerably greater brake pedal
force is required and the stopping dis-
tance is increased.
Stop the vehicle in a safe location or as
soon as it is safe to do so.
Apply the parking brake (page 68).
 Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise the
engine will overheat due to an inoperative
water pump which may result in damage
to the engine. Notify an authorized
Mercedes-Benz Light Truck Center.
If it is intact:
Drive immediately to the nearest
authorized Mercedes-Benz Light Truck
Center. Adjust driving to be consistent
with reduced braking responsiveness.

472 Practical hints
What to do if …
Display symbolDisplay messagesPossible cause/consequencePossible solution
;(USA only)
3(Canada only)
Check
brake fluid levelThere is insufficient brake fluid
in the reservoir.Risk of accident! Stop the vehicle in a
safe location or as soon at is safe to do
so.
Apply the parking brake (page 68).
Notify an authorized Mercedes-Benz
Light Truck Center. Do not add brake
fluid! This will not solve the problem.
? (USA only)
± (Canada only)
Engine
ServiceThere may be a malfunction in
the

fuel injection system

ignition system

exhaust system

fuel system
Have the engine checked by an
authorized Mercedes-Benz Light Truck
Center.
Warning!G
Driving with the message Check brake
fluid level
displayed can result in an ac-
cident. Have your brake system checked im-
mediately. Do not add brake fluid before
checking the brake system. Overfilling the
brake fluid reservoir can result in spilling
brake fluid on hot engine parts and the
brake fluid catching fire. You could be seri-
ously burned.!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.

473 Practical hints
What to do if …
Display symbolDisplay messagesPossible cause/consequencePossible solution
Ï Coolant level
Stop car, switch engine offThe coolant is too hot.
Among other possible causes
(the cooling fan could be
malfunctioning), the poly-V-belt
could be broken.Stop the vehicle in safe location or as
soon as it safe to do so.
Apply the parking brake (page 68).
Turn off the engine.
Check the poly-V-belt.
If it is broken:
Do not continue to drive. Otherwise, the
engine will overheat due to an inoperative
water pump which may result in damage
to the engine. Contact an authorized
Mercedes-Benz Light Truck Center.
If it is intact:
Do not continue to drive the vehicle with
this message displayed. Doing so could
result in serious engine damage that is
not covered by the Mercedes-Benz Limit-
ed Warranty.
(Continued on next page)

475 Practical hints
What to do if …
Display symbolDisplay messagesPossible cause/consequencePossible solution
B Top up Coolant
See Oper. ManualThe coolant level is too low.Add coolant (page 382).
If you have to add coolant frequently,
have the cooling system checked by an
authorized Mercedes-Benz Light Truck
Center.
Warning!G
Do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. You could be seriously burned.
!Do not ignore the low engine coolant level
warning. Extended driving with the message and
symbol displayed may cause serious engine
damage not covered by the Mercedes-Benz
Limited Warranty.
Do not drive without sufficient amount of coolant
in the cooling system. The engine will overheat
causing major engine damage.

476 Practical hints
What to do if …
When the message Add 1 qt. engine oil
at next refueling
(Canada: 1 liter)
appears while the engine is running and at
operating temperature, the engine oil level
has dropped to approximately the mini-
mum level.
When this occurs, the warning will first
come on intermittently and then stay on if
the oil level drops further.Visually check for oil leaks. If no obvious oil
leaks are noted, drive to the nearest
service station where the engine oil should
be topped to the required level with an
approved oil.
For information on approved engine oils,
refer to the Factory Approved Service
Products pamphlet (USA only) or contact
an authorized Mercedes-Benz Light Truck
Center.
Display symbolDisplay messagesPossible cause/consequencePossible solution
NCheck eng. oil level
at next refuelingThe engine oil level is too low.Check the engine oil level (page 381).
USA only:
Add 1 qt. engine oil
at next refueling
Canada only:
Add 1 liter engine oil
at next refueling
The engine oil level is too low.Add engine oil (page 382) and check
the engine oil level (
page 381).
Engine oil level
cannot be measuredThe measuring system is
malfunctioning.Have the measuring system checked by
an authorized Mercedes-Benz Light Truck
Center.

493 Practical hints
What to do if …
Display symbolDisplay messagesPossible cause/consequencePossible solution
kDiff. lock system malfunct.
Visit workshopThe differential locks* are
malfunctioning.Do not drive faster than 50 mph
(80 km/h).
Have the vehicle checked at an autho-
rized Mercedes-Benz Light Truck
Center.
Diff. Lock System
overheated. Wait briefly.The differential locks* are too hot
and have been deactivated as a re-
sult.Continue driving with added caution.
The lock function is unavailable.
Wait for the lock system to cool down.
The differential locks will be reactivat-
ed as soon as they have cooled off.
mStop vehicle
Engage parking brakeA shifting procedure could not be
completed. LOW RANGE* is in neu-
tral position. There is no connection
between the engine and the drive
wheels.Do not attempt to continue driving.
You could otherwise damage the
vehicle’s drivetrain.
Let the vehicle coast to a halt.
 Engage the parking brake.
Perform the shifting procedure again
(
page 204).

531 Practical hints
Battery
!The battery is a valve-regulated lead acid
(VRLA) battery, also referred to as “fleece” bat-
tery. Such batteries do not require topping-up of
the electrolyte level. VRLA batteries therefore do
not have cell caps and the battery cover is
non-removable. Do not attempt to open the bat-
tery as otherwise the battery will be damaged.
Even though VRLA batteries do not require top-
ping-up of the electrolyte level and cannot be
opened to check the electrolyte level, the bat-
tery condition must be checked periodically by
performing a battery conductance test. Refer to
Maintenance Booklet for battery condition test-
ing intervals.
As with any other battery, the battery may dis-
charge if the vehicle is not operated for an ex-
tended period of time. You can connect a battery
maintenance charge unit tested and approved
for use on your vehicle model or disconnect the
battery to prevent battery discharge. Contact an
authorized Mercedes-Benz Light Truck Center
for more information.!The factory-equipped VRLA battery is
leak-proofed. Only use a battery as replacement
that has the same security features and is of
identical size, voltage, and capacity as the
factory-equipped battery.
The battery, the battery ventilation hose
(
page 536) and the lateral plug (page 536)
must always be securely installed when the
vehicle is in operation.
Warning!G
Jump starting must only be done using the
jump-start contacts located in the engine
compartment (
page 538).
Warning!G
Failure to follow these instructions can re-
sult in severe injury or death.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 530).
Never lean over batteries while connecting,
you might get injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come in contact with eyes,
skin or clothing. In case it does, immediately
flush affected area with water and seek
medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking etc.

532 Practical hints
Battery
Disconnecting, removing, reinstalling
and reconnecting the battery
Step 1 (Disconnecting)
Set the automatic transmission to
positionP (
page 194).
Firmly depress the parking brake
(
page 68).
Turn off the engine (page 69).
Leave the ignition switched on
(
page 42).
!Never loosen or detach battery terminal
clamps while the engine is running or the
SmartKey is in the starter switch. Otherwise the
alternator and other electronic components
could be severely damaged.
Have the battery checked regularly by an
authorized Mercedes-Benz Light Truck Center.
Contact your authorized Mercedes-Benz Light
Truck Center for further information.
Warning!G
Do not place metal objects on the battery as
this could result in a short circuit.
Use leak-proof battery only to avoid the risk
of acid burns in the event of an accident.
Warning!G
Disconnecting, removing, reinstalling and
reconnecting the battery is a complicated
and technically demanding procedure that
a l s o r e q u i r e s s a f e t y p r e c a u t i o n s t o a v o i d t h e
risk of injury. We strongly recommend that it
be performed by a qualified technician or an
authorized Mercedes-Benz Light Truck
Center only. Please read the instructions
fully before beginning operation and only
undertake it if you feel fully capable of
performing all of the tasks involved as de-
scribed in these instructions. Observe all
safety instructions and precautions when
handling automotive batteries
(
page 530). Performing the tasks involved
incorrectly can cause damage to the vehicle
and impair the operating safety of the
vehicle, and/or cause severe injury to you
or others.
iWith a disconnected battery you will no
longer be able to turn the SmartKey in the starter
switch and pressing the KEYLESS-GO*
start/stop button will have no effect.
iIf your battery is discharged, the vehicle
must be jump started (
page 538) using the
jump start contacts in the engine compartment,
or an accessory battery charge unit* approved
by Mercedes-Benz must be connected using the
jump start contacts in the engine compartment
(see separate instructions for the accessory bat-
tery charge unit*) before any of the following
steps can be performed. If the battery cannot be
jumped or charged, please contact an
authorized Mercedes-Benz Light Truck Center.

538 Practical hints
Jump starting
If the battery is discharged, the engine can
be started with jumper cables and the bat-
tery of another vehicle. Observe the follow-
ing:

Jump starting should only be performed
using the jump-start contacts located
in the engine compartment
(
page 539).

Jump starting should only be performed
when the engine and catalytic
converter
1 are cold.

Do not start the engine if the battery is
frozen. Let the battery thaw out first.

Only jump start from batteries with the
same voltage rating (12 V). Jump start-
ing with a higher voltage battery could
damage the vehicle’s electrical system,
which will not be covered by the
Mercedes-Benz Limited Warranty.

Only use jumper cables with sufficient
cross-section and insulated terminal
clamps.

Always make sure the jumper cables
are not on or near pulleys, fans or other
parts that move when the engine is
started or running.
Warning!G
Failure to follow these directions will cause
damage to the electronic components, and
can lead to a battery explosion and severe
injury or death.
Never lean over batteries while connecting
or jump starting, you might get injured.
Battery fluid contains sulfuric acid. Do not
allow this fluid to come in contact with eyes,
skin or clothing. In case it does, immediately
flush affected area with water, and seek
medical help if necessary.
A battery will also produce hydrogen gas,
which is flammable and very explosive. Keep
flames or sparks away from battery, avoid
improper connection of jumper cables,
smoking, etc.
Attempting to jump start a frozen battery
can result in it exploding, causing personal
injury.
Read all instructions before proceeding.
1Vehicles with gasoline engine only.
!Do not tow-start the vehicle.
!Avoid repeated and lengthy starting
attempts.
Do not attempt to start the engine using a
battery quick charge unit.
If the engine does not run after several unsuc-
cessful starting attempts, have it checked at the
nearest authorized Mercedes-Benz Light Truck
Center.
Excessive unburned fuel generated by repeated
failed starting attempts may damage the catalyt-
ic converter
1.
Make sure the jumper cables do not have loose
or missing insulation.
Make sure the cable clamps do not touch any
other metal part while the other end is still at-
tached to a battery.

539 Practical hints
Jump starting
The jump-start contacts are located in the
engine compartment.
1Negative (-) terminal
2Positive (+) terminal
3Positive terminal cover
Make sure the two vehicles do not
touch.
Turn off all electrical consumers.
Apply parking brake (page 68).
Set automatic transmission to
positionP (
page 194).
Open the hood (page 379).
Remove cover from negative
terminal1.
Flip up cover3 of positive terminal2
in direction of arrow.
1Negative terminal of discharged
battery
2Positive terminal of discharged battery
4Positive terminal of charged battery
5Negative terminal of charged battery
Connect positive terminal2 and4
with the jumper cable. Clamp cable to
charged battery4 first.
Start engine of the vehicle with the
charged battery and run at idle speed.
Connect negative terminals1 and5
of the batteries with the second jumper
cable. Clamp the cable to negative
terminal5 of the charged battery
first.
Start the engine of the disabled vehi-
cle.
You can now turn on the electrical consum-
ers. Do not switch on the headlamps under
any circumstances.
Remove the jumper cables first from
negative terminals1 and5 and then
from positive terminals2 and4.
You can now switch on the headlamps.
Have the battery checked at the near-
est authorized Mercedes-Benz Light
Truck Center.
Warning!G
Keep flames or sparks away from battery.
Do not smoke.
Observe all safety instructions and precau-
tions when handling automotive batteries
(
page 530).
!Never invert the terminal connections!