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Safety and Security
Driving safety systems
The electrohydraulic brake servo assis-
tance switches off automatically
ț approximately 2 minutes after you
turned the SmartKey in the starter
switch to position 0 or removed the
SmartKey
ț approximately 2 minutes after you
pressed the KEYLESS-GO* start/stop
button to turn off the engine or power
supply and opened the driver’s door
(with driver’s door open, the starter
switch is set to position 0, same as
SmartKey removed from starter
switch)
ț approximately 20 seconds after you
locked the vehicle from outside
i
If the electrohydraulic brake system is
activated as the brake pedal is first de-
pressed, you may feel a reduced pedal
resistance and longer pedal travel than
normal. When releasing the pedal, you
may also feel the brake pedal pulsate
and you may hear a sound which is
caused by the activation of the electro-
hydraulic brake system pump. This is
normal and not an indication of a mal-
function. Pedal travel returns to normal
when you release the brake pedal and
the sound soon ceases.
If you experience the above while driv-
ing and the red brake warning lamp
(
୴ page 374) illuminates and/or warn-
ing messages appear in the instrument
cluster (
୴ page 383), the brake system
is malfunctioning. Follow the instruc-
tions of the warning message(s) and
have the brake system checked imme-
diately.
Warning! G
Have brake pad replacement and other work
on the electrohydraulic brake system car-
ried out by qualified technicians only. Con-
tact an authorized Mercedes-Benz Center
for further information. The electrohydraulic
brake system must be deactivated prior to
working on the system. High pressure is in-
termittently built up in the system as part of
its automatic self-test. In addition, the sys-
tem is automatically activated when the ve-
hicle is unlocked by SmartKey, when the
driver or passenger door is opened, when
the starter switch is turned to position
1,
when the brake pedal is depressed or when
the parking brake is released. Failure to de-
activate the system prior to maintenance
will cause brake pistons to extend and brake
fluid to leak, which may result in injuries
(contusions and acid burns). Extended
brake pistons may also cause injury.