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218Driving and operating
Checking the tensioning of the
coupling ball bar
■ Red marking on rotary knob must
point towards green marking on
coupling ball bar.
■ The gap between the rotary knob and the coupling ball bar must beapprox. 6 mm.
■ The key must be in position c.
Otherwise, the coupling ball bar must be tensioned before being inserted:
■ Unlock coupling ball bar by turning key to position c.
■ Pull out rotary knob and turn
clockwise as far as it will go.
Inserting the coupling ball bar
Insert the tensioned coupling ball bar
in the opening and push firmly
upwards until it audibly engages.
The rotary handle snaps back into its
original position resting against the
coupling ball bar without a gap.9 Warning
Do not touch rotary handle during
insertion.
Lock the coupling ball bar by turning
the key to position e. Remove the key
and close the protective flap.
Page 221 of 299

Driving and operating219
Eye for break-away stopping cable
Attach breakaway stopping cable to
eye.
Check that the coupling ball bar is correctly installed
■ Green marking on rotary knob must
point towards green marking on
coupling ball bar.
■ There must be no gap between the
rotary handle and the coupling ball
bar.
■ The coupling ball bar must be firmly
engaged in the opening.
■ The coupling ball bar must be locked and the key removed.9 Warning
Towing a trailer is permitted only
when a coupling ball bar is fitted correctly. If the coupling ball bardoes not engage correctly, seekthe assistance of a workshop.
Dismounting the coupling ball
bar
Open the protective flap and turn the
key to position c to unlock the
coupling ball bar.
Pull out rotary handle and turn
clockwise as far as it will go. Pull out coupling ball bar downwards.
Insert sealing plug in opening. Fold away socket.
Trailer stability assist If the system detects snaking
movements, engine power is reduced
and the vehicle/trailer combination is
selectively braked until the snaking ceases. While system is working keep steering wheel as still as possible.
Trailer stability assist (TSA) is a
function of the Electronic Stability
Control 3 174.
Page 231 of 299
Vehicle care229Bulb replacement
Switch off the ignition and switch off
the relevant switch or close the doors.
Only hold a new bulb at the base. Do
not touch the bulb glass with bare
hands.
Use only the same bulb type for
replacement.
Replace headlight bulbs from within
the engine compartment.
Halogen headlightsBi-Halogen headlight (1) with one
bulb for low and high beam.
Front turn signal (2) .
Sidelight/Daytime running light (3) .
Low/High beam (1) 1. Rotate the cap (1) anticlockwise and remove it.
2. Rotate the bulb holder anticlockwise to disengage.
Withdraw the bulb holder from the
reflector.
3. Disengage the bulb holder from the plug connector by pressing
the retaining lug.
4. Replace the bulb and connect bulb holder to the plug connector.
5. Insert the bulb holder, engaging the two lugs into the reflector androtate clockwise to secure.
6. Fit the cap and rotate clockwise.
Page 232 of 299
230Vehicle care
Front turn signal (2)
1. Rotate bulb socket (2)anticlockwise to disengage.
Withdraw the bulb socket from the
reflector.
2. Remove the bulb from the socket by turning anticlockwise.
3. Replace and insert new bulb into socket by turning clockwise.
4. Insert the bulb socket into the reflector and turn clockwise.
Sidelight/Daytime running light
(3)
1. Rotate bulb socket (3) anticlockwise to disengage.
Withdraw the bulb socket from the
reflector.
Page 233 of 299
Vehicle care231
2. Remove the bulb from the socketby pulling.
3. Replace and insert new bulb into socket.
4. Insert the bulb socket into the reflector and turn clockwise.
Adaptive forward lighting9 Danger
Adaptive forward lighting system
uses Xenon headlights.
Xenon headlights work under
extremely high electrical voltage.
Do not touch. Have bulbs replaced by a workshop.
Bulbs for front turn signal and
corner lighting can be replaced.
Corner lighting (1) .
Front turn signal (2) .
Sidelight/Daytime running lights are
designed as Light Emitting Diodes
(LEDs) and cannot be replaced.
Corner lighting (1) 1. Rotate the cap (1) anticlockwise and remove it.
2. Rotate the bulb holder anticlockwise to disengage.
Withdraw the bulb holder from the
reflector.
Page 234 of 299
232Vehicle care
3. Disengage the bulb from the plugconnector by pulling.
4. Replace the bulb and connect bulb holder to the plug connector.
5. Insert the bulb holder, engaging the two lugs into the reflector and
rotate clockwise to secure.
6. Fit the cap and rotate clockwise.
Front turn signal (2)
1. Rotate bulb socket (2) anticlockwise to disengage.
Withdraw the bulb socket from the
reflector.
2. Remove the bulb from the socket by turning anticlockwise.
3. Replace and insert new bulb into socket by turning clockwise.
4. Insert the bulb socket into the reflector and turn clockwise.
Fog lights The bulbs are accessible from
beneath the vehicle.
Page 235 of 299
Vehicle care233
1. Remove the outer screws of thecover, marked by the arrows.
2. Hinge away the cover.
Turn the bulb socket
anticlockwise and remove it from
the reflector.
3. Disengage the bulb socket from the plug connector by pressing
the retaining lug.
4. Remove and replace the bulb socket with bulb and attach to the
plug connector.
5. Insert the bulb socket into the reflector, turn clockwise and
engage.
6. Mount the cover with the screws.
Tail lights
1. Hinge out the screw cover.
Page 237 of 299
Vehicle care235
Reverse lights (4) in the tailgate
1.Open the tailgate and remove the
cover.
2. Turn the bulb holder anticlockwise
and remove it from the reflector.
3. Remove the bulb from the socket by pulling.
4. Replace and insert new bulb into socket.
5. Insert the bulb socket into the reflector and turn clockwise.
6. Install the cover.
Rear fog light The bulbs are accessible from
beneath the vehicle.
1. Turn the bulb socket anticlockwise and remove it from
the reflector.