191 Controls in detail
Audio system
Connecting an external audio source 
(AUX) to the radio*
An optional dealer-installed cinch-connec-
tor* for connecting an external audio 
source may become available for your 
vehicle model. Feature description is 
based on preliminary information at time 
of printing. Contact an authorized 
Mercedes-Benz Center for availability.
You can adjust the volume (
page 187), 
the sound settings (
page 187) and the 
volume distribution (page 189) for the 
AUX input.
Calling up AUX mode
Press and hold Q button until AUX 
appears in the display.
Canceling AUX mode
Press any audio source button.
Radio operation
Selecting radio mode
Press b button.
Calling up wavebands
You can choose from among the FM, AM 
and WB wavebands.
Weather band (
page 195).Calling up wavebands for radios 
without SAT
Press 
FM or 
AM soft key to switch 
between FM and AM.
The FM and AM wavebands are called 
up one after another.
or
Press 
WB soft key.
The weather band menu is called up.
The waveband currently selected 
appears in the upper left-hand corner 
of the display.
iFM waveband: 87.7......107.9 MHz
AM waveband: 530......1 710 KHz 
247 Controls in detail
Useful features
Push down cover plate1 to close 
ashtray.
The cover plate engages.Electrical outlet in the rear passenger 
compartment
1Electrical outlet
2Cover
Switch on ignition (
page 33).
Pull at top of cover2.
Flip cover1 to the left and insert 
electrical plug (cigarette lighter type).
Telephone*
Radio transmitters, such as a portable tele-
phone or a citizens band unit, should only 
be used inside the vehicle if they are con-
nected to an antenna that is installed on 
the outside of the vehicle.
The external antenna must be approved by 
Mercedes-Benz. Please contact an autho-
rized Mercedes-Benz Center for informa-
tion on the installation of an approved 
external antenna. Refer to the radio trans-
mitter operation instructions regarding use 
of an external antenna.
Warning!
G
Never touch the heating element or sides of 
the lighter; they are extremely hot. Hold the 
knob only.
When leaving the vehicle, always remove the 
SmartKey from the starter switch, and lock 
your vehicle. Do not leave children unat-
tended in the vehicle, or with access to an 
unlocked vehicle. Unsupervised use of vehi-
cle equipment may cause an accident 
and/or serious personal injury.iThe lighter socket can be used to 
accommodate electrical accessories 
up to a maximum 85 W.
iThe electrical outlet can be used to 
accommodate electrical consumers 
(e.g. air pump, auxiliary lamps) up to a 
maximum of 180 W.
Warning!
G
Never operate radio transmitters equipped 
with a built-in or attached antenna (i.e. with-
out being connected to an external antenna) 
from inside the vehicle while the engine is 
running. Doing so could lead to a malfunc-
tion of the vehicle’s electronic system, pos-
sibly resulting in an accident and personal 
injury.