2008 MERCEDES-BENZ C300 Alarm button

58 Safety and Security
Panic alarm
1Â button
Activating: Press and hold  but-
ton for at least 1 second.
An audible alarm and flashing exterior
lamps will operate briefly.
Deactivating: Press  button
again.
or
Insert the SmartKey or the SmartKey
with KEYLESS-GO* (Canada only) in
starter switch.
or
Press the KEYLESS-GO* start/stop
button (Canada only) (
page 84).
The SmartKey with KEYLESS-GO*
(Canada only) must be inside the
vehicle.
iUSA only:
This device complies with Part 15 of the FCC
Rules. Operation is subject to the following two
conditions:
(1) This device may not cause harmful interfer-
ence, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
iCanada only:
This device complies with RSS-210 of Industry
Canada. Operation is subject to the following
two conditions:
(1) This device may not cause interference, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation of the device.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.

66 Safety and Security
Anti-theft systems
Immobilizer
The immobilizer prevents unauthorized
persons from starting your vehicle.
When leaving the vehicle, always take the
SmartKey or SmartKey with KEYLESS-GO*
(Canada only) with you and lock the
vehicle. The engine can be started by
anyone with a valid SmartKey or SmartKey
with KEYLESS-GO* (Canada only) that is
left inside the vehicle.
Activating
With the SmartKey: Remove the
SmartKey from the starter switch.
With the KEYLESS-GO* (Canada
only): Turn off the engine and open the
driver’s door.
Deactivating
Switch on the ignition.
Anti-theft alarm system
Once the alarm system has been armed, a
visual and audible alarm is triggered when
someone opens:

a door

the trunk

the hood
The alarm will stay on even if the activating
element (a door, for example) is immedi-
ately closed.
The alarm system will also be triggered
when

the vehicle is opened with the
mechanical key.

a door is opened from the inside.

the trunk is opened with the
emergency release button.
To cancel the alarm after it has been trig-
gered, see “Canceling the alarm”
(
page 67).
1Indicator lamp
iStarting the engine will also deactivate the
immobilizer.
In case the engine cannot be started (yet the
vehicle’s battery is charged), the system is not
operational. Contact an authorized
Mercedes-Benz Center or call
1-800-FOR-MERCedes (in the USA), or
1-800-387-0100 (in Canada).
iIf the alarm stays on for more than
30 seconds, a call to the Response Center is
initiated automatically by the Tele Aid* system
(
page 295) provided Tele Aid* service was
subscribed to and properly activated, and that
necessary mobile phone, power supply and GPS
coverage are available.

67 Safety and Security
Anti-theft systems
Arming: Lock the vehicle with the
SmartKey or KEYLESS-GO* (Canada
only).
The turn signal lamps flash three times,
and an acoustic signal sounds three
times, to indicate that the alarm sys-
tem is armed.
Indicator lamp1 begins to flash after
approximately 15 seconds after arming
the alarm system.
Disarming: Unlock your vehicle with
the SmartKey or KEYLESS-GO*
(Canada only).
The turn signal lamps flash once, and
an acoustic signal sounds once, to
indicate that the alarm system is
disarmed.
Canceling the alarm
To cancel the alarm, do one of the
following:
Insert the SmartKey or SmartKey with
KEYLESS-GO* (Canada only) in the
starter switch.
or
Press the Œ or ‹ button on the
SmartKey or SmartKey with
KEYLESS-GO* (Canada only).
In vehicles with KEYLESS-GO* (Canada
only):
Grasp an outside door handle.
The SmartKey with KEYLESS-GO
(Canada only) must be within 3 ft (1 m)
of the vehicle.
or
Press the KEYLESS-GO (Canada only)
start/stop button (
page 84).
The SmartKey with KEYLESS-GO
(Canada only) must be inside the vehi-
cle.
iIf the turn signal lamps do not flash three
times, and the acoustic signal does not sound
three times, one of the following elements may
not be properly closed:

a door

the trunk
the alarm system is armed.
With a door open, close the door and lock the ve-
hicle again. The turn signal lamps flash three
times, and an acoustic signal sounds three
times, to indicate that the alarm system is armed
and the vehicle is locked. If you open the un-
locked door again the alarm system will be trig-
gered.With the trunk open, close the trunk lid. The ve-
hicle will lock and the turn signal lamps flash
three times, and an acoustic signal sounds three
times, to indicate that the alarm system is armed
and the vehicle is locked.
iThe vehicle will lock and the alarm system
will rearm automatically after approximately 40
seconds if neither a door nor the trunk lid was
opened.

71 Controls in detail
Locking and unlocking
Factory setting
Global unlocking: Press buttonŒ.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knobs in the doors
move up.

The anti-theft alarm system is dis-
armed.

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).
iUSA only:
This device complies with Part 15 of the FCC
Rules. Operation is subject to the following two
conditions:
(1) This device may not cause harmful interfer-
ence, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
iCanada only:
This device complies with RSS-210 of Industry
Canada. Operation is subject to the following
two conditions:
(1) This device may not cause interference, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation of the device.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
iYou can also open and close the door win-
dows and tilt/sliding sunroof, or the panorama
roof with power tilt/ sliding panel* using the
SmartKey (
page 123).
!If you cannot lock or unlock the vehicle with
the SmartKey, then either the batteries in the
SmartKey are discharged, the SmartKey is mal-
functioning or the vehicle batteries are drained.

Check the batteries in the SmartKey and re-
place them if necessary (
page 428).

Use the mechanical key to unlock the driv-
er’s door (
page 424) and trunk
(
page 425).

Use the mechanical key to lock and trunk
(
page 272).

Have the vehicle batteries and their connec-
tions checked (
page 446).
If the SmartKey is malfunctioning, contact
Roadside Assistance or an authorized
Mercedes-Benz Center.
iYour vehicle is equipped with an acoustic
lock and unlock confirmation signal feature. An
acoustic signal will sound when the vehicle is
locked or unlocked using the SmartKey.
If you wish to activate or deactivate the feature,
or adjust its signal volume, contact an authorized
Mercedes-Benz Center.

72 Controls in detail
Locking and unlocking
The vehicle will lock again automatically
and rearm the anti-theft alarm system
within approximately 40 seconds of un-
locking if:

neither a door nor the trunk is opened

the SmartKey is not inserted in the
starter switch

the central locking/unlocking switch is
not activated
Global locking: Press button‹.
With the trunk and doors closed:

All turn signal lamps flash three
times.

An acoustic signal sounds three
times.

The locking knobs in the doors
move down.

The anti-theft alarm system is
armed.Selective setting
If you frequently travel alone, you may wish
to reprogram the SmartKey so that press-
ing buttonŒ only unlocks the driver’s
door and the fuel filler flap.
Press and hold buttonsŒ and‹
simultaneously for about 6 seconds un-
til battery check lamp5 (
page 70)
flashes twice.
The SmartKey will then function as fol-
lows:
Unlocking driver’s door and fuel fill-
er flap: Press buttonΠonce.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knob in the driver’s
door moves up.

The anti-theft alarm system is dis-
armed.

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).
Global unlocking: Press buttonŒ
twice.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knobs in the doors
move up.

The anti-theft alarm system is dis-
armed.

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).

73 Controls in detail
Locking and unlocking
Global locking: Press button‹.
With the trunk and doors closed:

All turn signal lamps flash three
times.

An acoustic signal sounds three
times.

The locking knobs in the doors
move down.

The anti-theft alarm system is
armed.
Restoring to factory setting: Press
and hold buttonsŒ and‹ si-
multaneously for about 6 seconds until
battery check lamp5 (
page 70)
flashes twice.SmartKey with KEYLESS-GO*
(Canada only)
Vehicles equipped with KEYLESS-GO come
with two SmartKeys with KEYLESS-GO,
each with remote control and a removable
mechanical key.
The KEYLESS-GO function is integrated
into the SmartKey. On these vehicles, the
validity of the SmartKey with KEYLESS-GO
is checked every time you grasp an outside
door handle.
With the KEYLESS-GO function, you can
lock and unlock the vehicle without using
the remote control buttons on the
SmartKey and start the engine without in-
serting the SmartKey in the starter switch.
The SmartKey with KEYLESS-GO centrally
locks and unlocks, when set to factory set-
tings (
page 76):

the doors

the trunk

the fuel filler flap
SmartKey with KEYLESS-GO
1‹ Lock button
2ŠOpening button for trunk
(
page 269)
3Locking tab for mechanical key
4ΠUnlock button
5Battery check lamp
6ÂPanic button (
page 58)
iWhen any outside door handle other than
the driver’s outside door handle is grasped, the
vehicle is always centrally unlocked.
!To prevent possible malfunction, avoid ex-
posing the SmartKey with KEYLESS-GO to high
levels of electromagnetic radiation.

77 Controls in detail
Locking and unlocking
Global unlocking: Grasp an outside
door handle1.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knobs in the doors
move up.

The anti-theft alarm system is dis-
armed.

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).
The vehicle will lock again automatically
and rearm the anti-theft alarm system
within approximately 40 seconds of un-
locking if:

neither a door nor the trunk is opened

the central locking/unlocking switch is
not activated
Global locking: Close all doors and
touch outside of door handle1. Do
not keep your hand in the door handle
recess.
With the trunk and doors closed:

All turn signal lamps flash three
times.

An acoustic signal sounds three
times.

The locking knobs in the doors
move down.

The anti-theft alarm system is
armed.Selective setting
If you frequently travel alone, you may wish
to reprogram the SmartKey with
KEYLESS-GO so when you, grasp the driv-
er’s outside door handle only the driver’s
door and the fuel filler flap unlocks.
Press and hold buttonsŒ and‹
simultaneously for about 6 seconds un-
til battery check lamp5 (
page 73)
flashes twice.
The SmartKey with KEYLESS-GO will
then function as follows:
Unlocking driver’s door and fuel fill-
er flap: Grasp the driver’s outside door
handle.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knob in the driver’s
door moves up.

The anti-theft alarm system is dis-
armed.
iThe vehicle could inadvertently be unlocked
if the SmartKey with KEYLESS-GO is within 3 ft
(1 m) of the vehicle and:

an outside door handle is splashed with wa-
ter, or

you attempt to clean an outside door handle.
iYou can also lock the vehicle using the
KEYLESS-GO lock button on trunk lid, if equipped
(
page 270).

78 Controls in detail
Locking and unlocking

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).
Global unlocking: Grasp any outside
door handle other than the driver’s out-
side door handle.

All turn signal lamps flash once.

An acoustic signal sounds once.

The locking knobs in the doors
move up.

The anti-theft alarm system is dis-
armed.

The locator lighting will also come
on if it is dark and the feature is ac-
tivated in the control system
(
page 172).
Global locking: Close all doors and
touch outside of a door handle1
(
page 76). Do not keep your hand in
the door handle recess.
With the trunk and doors closed:

All turn signal lamps flash three
times.

An acoustic signal sounds three
times.

The locking knobs in the doors
move down.

The anti-theft alarm system is
armed.
Restoring to factory setting: Press
and hold buttonsŒ and‹ si-
multaneously for about 6 seconds until
battery check lamp5 (
page 73)
flashes twice.Checking batteries in the SmartKey or
SmartKey with KEYLESS-GO*
(Canada only)
Press button‹ orŒ.
The battery check lamp (
page 70) or
(
page 73) comes on briefly to indi-
cate that the SmartKey or SmartKey
with KEYLESS-GO batteries are in or-
der.
iYou can also lock the vehicle using the
KEYLESS-GO lock button on trunk lid, if equipped
(
page 270).!If the battery check lamp does not come on
briefly during check, the SmartKey or SmartKey
with KEYLESS-GO batteries are discharged.
Replace the batteries (
page 428).
You can obtain the required batteries at any
authorized Mercedes-Benz Center.
iIf the batteries are checked within signal
range of the vehicle, pressing button‹ or
Πwill lock or unlock the vehicle accordingly.