2008 MERCEDES-BENZ SL550 alternator

344 Practical hints
What to do if …
ProblemPossible cause/consequenceSuggested solution
-The yellow ABS indicator lamp
comes on when the engine is
running.The ABS has detected a malfunction and has
switched off. The BAS and the ESP® are also
switched off (see messages in display).
The electro-hydraulic brake system is still
functioning normally but without the ABS
available.
If the ABS control unit is malfunctioning, oth-
er systems such as Parktronic*, Distronic*,
or the automatic transmission may also be
malfunctioning.
Continue driving with added caution.
Wheels may lock during hard braking,
reducing steering capability.
Have the system checked at an autho-
rized Mercedes-Benz Center as soon
as possible.
Failure to follow these instructions in-
creases the risk of an accident.
Read and observe messages in the
display (
page 359).
The charging voltage has fallen below
10 volts and the ABS was switched off.
The battery may not be sufficiently charged.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
battery checked.

376 Practical hints
What to do if …
Symbol messages
Left displayRight displayPossible 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 capa-
bility. Considerably greater brake
pedal force is required and the stop-
ping distance is increased.
Stop the vehicle immediately in a safe loca-
tion and 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 Center.
If it is in order:
Contact an authorized Mercedes-Benz
Center immediately. Adjust driving to be
consistent with reduced braking respon-
siveness.
There is a malfunction in the elec-
tronic system.Have the system checked at an authorized
Mercedes-Benz Center as soon as possible.

377 Practical hints
What to do if …
Left displayRight displayPossible cause/consequencePossible solution
# Battery/
Alternator
Stop CarThe battery is malfunctioning.
The electro-hydraulic brake system
requires electrical energy and
therefore has only limited opera-
tion. Considerably greater brake
pedal force is required and the stop-
ping distance is increased.Stop the vehicle in a safe location.
Adjust driving to be consistent with reduced
braking responsiveness.
Contact an authorized Mercedes-Benz
Center.
USA only:
;
Canada only:
3
Reduced
Brake Effect
Start EngineThe battery has insufficient voltage
and cannot supply sufficient power
to the electro-hydraulic brake sys-
tem.Start the engine.
The message disappears when sufficient
voltage is available.
Warning!G
Inhalation of exhaust gas is hazardous to
your health. All exhaust gas contains carbon
monoxide (CO), and inhaling it can cause
unconsciousness and lead to death. Do not
run the engine in confined areas (such as a
garage) which are not properly ventilated.

428 Practical hints
Batteries
!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 and the
lateral plug must always be securely installed
when the vehicle is in operation.
Warning!G
Failure to follow these instructions can
result in severe injury or death.
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.
!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 starter battery checked regularly by an
authorized Mercedes-Benz Center.
Refer to Maintenance Booklet for maintenance
intervals or contact an authorized
Mercedes-Benz 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 batteries only to avoid the
risk of acid burns in the event of an acci-
dent.
Warning!G
The brake system requires electrical power
to operate.
A malfunction in the vehicle’s power supply
or electrical system may impair brake sys-
tem operation and switch it into its emer-
gency operation mode. The same applies if
battery is disconnected. To brake, the driver
must then apply significantly greater brake
pedal pressure and depress the pedal much
further to obtain the expected braking ef-
fect. If necessary, apply full pressure to the
brake pedal. Brakes are only applied to the
front wheels.
Stopping distance is increased! Adjust your
driving style accordingly. For more informa-
tion, see “Electro-hydraulic brake system”
(
page 94).

446 Technical data
Layout of poly-V-belt drive
SL 550
1Idler pulley
2Idler pulley
3Automatic belt tensioner
4ABC tandem pump (pump for
power-steering assistance and ABC
chassis)
5Air conditioning compressor
6Crankshaft
7Coolant pump
8Generator (alternator)SL 55 AMG
The SL 55 AMG has two poly-V-belts (belt
one shown in purple/belt two shown in
black).
1Idler pulley
2Automatic belt tensioner
3ABC tandem pump (pump for
power-steering assistance and ABC
chassis)
4Air conditioning compressor
5Crankshaft
6Coolant pump
7Generator (alternator)
8Idler pulley
9Automatic belt tensioner
aSupercharger
SL 600, SL 65 AMG
1Automatic belt tensioner
2ABC tandem pump (pump for
power-steering assistance and ABC
chassis)
3Air conditioning compressor
4Crankshaft
5Coolant pump
6Generator (alternator)
7Idler pulley
8Idler pulley
9Idler pulley

454 Technical data
Electrical system
ModelSL 550SL 600SL 55 AMGSL 65 AMG
Generator (alternator)14 V/180 A14 V/180 A14 V/180 A14 V/180 A
Starter motor12 V/1.7 kW12 V/1.7 kW12 V/1.7 kW12 V/1.7 kW
Starter battery12 V/35 Ah12 V/35 Ah12 V/35 Ah12 V/35 Ah
Battery for electrical consumers12 V/70 Ah12 V/70 Ah12 V/70 Ah12 V/70 Ah
Spark plugsNGK PLKR7ANGK IFR6QGNGK ILFR6ANGK IFR6QG
Electrode gap0.031 in (0.8 mm)0.028 in (0.7 mm)0.031 in (0.8 mm)0.028 in (0.7 mm)
Tightening torque15 – 18 lb-ft
(20 – 25 Nm)18 – 22 lb-ft
(25 – 30 Nm)18 – 22 lb-ft
(25 – 30 Nm)18 – 22 lb-ft
(25 – 30 Nm)