Page 375 of 498
373 Practical hints
What to do if …?
Symbol messagesDisplay symbol
Display message
Possible cause
Possible solution
#
Visit Workshop!
The battery is no longer charging.
Possible causes:
broken poly-V-belt
alternator malfunctioning
Stop immediately 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. Notify 
an authorized Mercedes-Benz Center.
If it is intact:
Drive immediately to the nearest 
authorized Mercedes-Benz Center.
Undervoltage
Charge battery
The battery has insufficient voltage.
Start the engine (
page 46).
Undervoltage
Switch off
consumers
The battery has insufficient voltage.
Turn off unnecessary electrical con-
sumers. 
     
        
        Page 422 of 498

420 Practical hintsBatteryThe battery is located in the engine 
compartment on the right hand side.
1Clamps
Removing filter box:
Release clamps1.
Remove filter box.
Installing filter box:
Insert filter box properly.
Secure it with clamps1.
Warning!
G
Failure to follow these instructions can re-
sult in severe injury or death.
Observe all safety instructions and 
precautions when handling automotive 
batteries (
page 314).
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 termi-
nal clamps while the engine is running 
or the SmartKey is in the starter switch. 
Otherwise the alternator and other 
electronic components could be se-
verely damaged.
Have the 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 battery only to avoid the risk 
of acid burns in the event of an accident. 
     
        
        Page 439 of 498
437 Technical data
Layout of poly-V-belt drive
Layout of poly-V-belt drive
CLK 320/CLK 500/CLK 55 AMG
1Automatic belt tensioner
2Power steering pump
3Air conditioning compressor
4Crankshaft
5Coolant pump
6Generator (alternator)
7Idler pulley 
     
        
        Page 446 of 498
444 Technical dataElectrical systemModel
CLK 320
CLK 500
CLK 55 AMG
Generator (alternator)
14 V/120 A
14 V/150 A
14 V/150 A
Starter motor
14 V/1.4 KW
14 V/1.7 KW
14 V/1.7 KW
Battery
12 V/100 Ah
12 V/100 Ah
12 V/100 Ah
Spark plugs
Bosch F8 DPP 332
NGK PFR 5R-11
Bosch F8 DPP 332
NGK PFR 5R-11
NGK ILFR 6A
Electrode gap
0.039 in (1.00 mm)
0.039 in (1.00 mm)
0.031 in (0.8 mm)
Tightening torque
18.5 - 22 lb-ft (25 - 30 Nm)
18.5 - 22 lb-ft (25 - 30 Nm)
18.5 - 22 lb-ft (25 - 30 Nm) 
     
        
        Page 460 of 498

458 Technical termsMultifunction steering wheel
Steering wheel with buttons for operat-
ing the control system.
OCS
(O
ccupant C
lassification S
ystem) 
The system automatically turns the 
front passenger front air bag on or off 
based on the classified occupant size 
category determined by weight sensor 
readings from the seat.
Overspeed range
Engine speeds within the red marking 
on the tachometer dial. Avoid this en-
gine speed range, as it may result in se-
rious engine damage that is not 
covered by the Mercedes-Benz Limited 
Warranty.Parktronic (Parking assist)*
System which uses visual and acoustic 
signals to assist the driver during park-
ing maneuvers.
Poly-V-belt drive
Drives engine-components (alternator, 
AC compressor, etc.) from the engine.
Power train
Collective term designating all compo-
nents used to generate and transmit 
motive power to the drive axles, includ-
ing
engine
clutch/torque converter
transmission
transfer case
drive shaft
differential
axle shafts/axlesProgram mode selector switch
Used to switch the automatic transmis-
sion between standard operationS and 
comfort operationC.
CLK 55 AMG with steering wheel gear-
shift control and manual shift program: 
In addition toS andC (for standardS 
or comfortC operation, see above) you 
can use theM for manual shift 
program.