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. 
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