2008 MERCEDES-BENZ ML550 alternator

400 Practical hints
What to do if …
Lamps in instrument clusterGeneral information:
If any of the following lamps in the instru-
ment cluster fails to come on during thebulb self-check when switching on the
ignition, have the respective bulb checked
and replaced if necessary.
ProblemPossible cause/consequenceSuggested solution
-The yellow ABS indicator lamp
comes on while the engine is
running.ABS has detected a malfunction and has
switched off. The BAS, ESP®, EBP, and 4-ETS
are also switched off (see messages in multi-
function display).
The brake system is still functioning normally
but without the ABS available.
If the ABS control unit is malfunctioning,
other systems such as the navigation
system* or the automatic transmission may
also be malfunctioning.
Continue driving with added caution.
Wheels may lock during hard braking,
reducing steering capability.
Read and observe messages in the
multifunction display (
page 413).
Have the system checked at an
authorized Mercedes-Benz Light
Truck Center as soon as possible.
Failure to follow these instructions
increases the risk of an accident.
The charging voltage has fallen below
10 volts. The ABS has switched off.
The battery might not be charged sufficiently.When the voltage is above this value
again, the ABS is operational again and
the ABS indicator lamp should go out.
If the ABS indicator lamp does not go out:
Have the generator (alternator) and
the battery checked.

419 Practical hints
What to do if …
Display messagePossible cause/consequencePossible solution
ESPUnavailable
See Operator’s ManualThe ESP® was deactivated because
of insufficient power supply. The
charging voltage has fallen below
10 volts.
The brake system is still functioning
normally but without the ESP
®
available.
When the voltage is above this value again, the
ESP® is operational again and the message in
the multifunction display should disappear.
If the message in the multifunction display does
not disappear:
Have the generator (alternator) and the
battery checked.
Have the system checked at an authorized
Mercedes-Benz Light Truck Center as soon
as possible.
If the yellow ESP® warning
lampv flashes while driving and
this message appears, the 4-ETS has
switched off to prevent overheating
of the drive wheel brakes.As soon as the brakes have cooled off, the
4-ETS switches on again.
The message in the multifunction display disap-
pears and the ESP
® warning lampv goes
out.
The self-diagnosis has not been
completed yet.The display will clear after driving a short
distance at a vehicle speed of above
12 mph (20 km/h).

427 Practical hints
What to do if …
Symbol messages
Display symbolDisplay messagePossible cause/consequencePossible solution
ò Replace air filter.The air filter is clogged.Have the air filter checked by an authorized
Mercedes-Benz Light Truck Center.
#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 65).
 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:
Drive immediately to the nearest authorized
Mercedes-Benz Light Truck Center. Adjust
driving to be consistent with reduced braking
responsiveness.

428 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
#Battery / Alternator
Stop VehicleThe battery is defective.Stop the vehicle in a safe location or as
soon as it is safe to do so.
Apply the parking brake (page 65).
Do not continue to drive.
Contact an authorized Mercedes-Benz
Light Truck Center.
{InoperativeDownhill Speed Regulation is
malfunctioning.Have the Downhill Speed Regulation
checked by an authorized Mercedes-Benz
Light Truck Center.
2Brake WearThe brake pads have reached
their wear limit.Have the brake pads replaced as soon as
possible.
!Brake pad thickness must be visually in-
spected by a qualified technician at the intervals
specified in the Maintenance Booklet.

491 Practical hints
Battery
Disconnecting, removing, reinstalling
and reconnecting the battery
Step 1 (Disconnecting)
Set the automatic transmission to
positionP (
page 185).
Firmly depress the parking brake
(
page 65).
Turn off the engine (page 66).
Leave the ignition switched on
(
page 40).
!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
also requires safety precautions to avoid the
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 489). 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 497) 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.


512 Technical data
Layout of poly-V-belt drive
ML 320 CDI
1Coolant pump
2Idler pulley
3Automatic belt tensioner
4Power steering pump
5Air conditioning compressor
6Crankshaft
7Idler pulley
8Generator (alternator)ML 350, ML 550
1Idler pulley
2Idler pulley
3Automatic belt tensioner
4Power steering pump
5Air conditioning compressor
6Crankshaft
7Coolant pump
8Generator (alternator)ML 63 AMG
1Idler pulley
2Idler pulley
3Idler pulley
4Automatic belt tensioner
5Power steering pump
6Air conditioning compressor
7Crankshaft
8Coolant pump
9Generator (alternator)

519 Technical data
Electrical system
Electrical system
ModelML 350ML 550ML 63 AMG
Generator (alternator)14 V/180 A14 V/180 A14 V/180 A
Starter motor12 V/1.4 kW12 V/1.7 kW12 V/2.1 kW
Battery12 V/70 Ah12 V/95 Ah12 V/95 Ah
Spark plugsBosch Y7MPP33NGK PLKR7A-1
1Contact an authorized Mercedes-Benz Light Truck Center.
Electrode gap0.031 in (0.8 mm)0.031 in (0.8 mm)0.039 in (1.0 mm)
Tightening torque15 – 19 lb-ft (20 – 25 Nm)15 – 19 lb-ft (20 – 25 Nm)15 – 22 lb-ft (20 – 30 Nm)
ModelML 320 CDI
Generator (alternator)14 V/180 A
Starter motor12 V/2.0 kW
Battery12 V/95 Ah