•

The convertible top well must be in the lower position.
The trunk lid must be closed.
The ambient temperature must be above 5 °F (-15 °C).
The battery voltage must be sufficient.

To lower the convertible top:
•
•

Insert the key in the driver’s door lock cylinder and turn
it in the “open” direction, then release.
Turn the key to the “open” direction again within 2
seconds and hold it in that position.

The convertible top cycle will start. The key must be held in
the “open” position during the convertible top cycle. If the
key is released, the cycle will immediately stop. To resume
the cycle, the key must again be turned in the “open” direction and held in that position.
If the key is turned in the “close” direction and held in this
position, the convertible top will close again.
623_057

Closing the convertible top with the vehicle key
The convertible top can also be closed using the car key.
Before this can be done, the following conditions must
be met:
• The trunk lid must be closed.
• The battery voltage must be sufficient.

To close the convertible top:
•
•

Insert the key in the driver’s door lock cylinder and turn
it in the “close” direction, then release.
Turn the key to the “close” direction again within 2
seconds and hold it in that position.

The convertible top cycle will start. The key must be held in
the “close” position during the convertible top cycle. If the
key is released, the cycle will immediately stop. To resume
the cycle, the key must again be turned in the “close”
direction and held in that position.
If the key is turned in the “open” direction and held in this
position, the convertible top will open again.
623_058

!
31

Note
When opening or closing the convertible top with the vehicle key, there may be a short delay between the time the key is
turned to when the operation begins.

Operating the convertible top while driving
The convertible top can be opened or closed using Power Top
Operation Switch E137 up to a speed of 31 mph (50 km/h).
If the vehicle speed increases to over 31 mph (50 km/h)
during the top cycle, the driver will be alerted both audibly
and visually. The top cycle is stopped and a the top comes
to a standstill in its current position. The cycle will not
resume until the vehicle speed has dropped below 31 mph
(50 km/h) or less.

Convertible top:
not in limit position.
Speed
too high

To do this, the operating switch must be kept pulled or pressed.

Message text

623_059

A convertible top cycle cannot be initiated if the vehicle is
travelling at a speed over 31 mph (50 km/h). In this case
too, the driver is alerted by audible and visual warnings.
Convertible top:
no operation
possible.
Speed
too high

Message text

623_060

32

Components of the convertible top control system
Power Top Operation Switch E137
The Power Top Operation Switch E137 is located in the
center console.

623_061

Power Top Operation Switch E137

Hall sensors
Controlled operation of the convertible top is only possible if
Convertible Top Control Module J256 receives information
from various sensors and switches during each phase of the
operating cycle. The sensors and switches indicate the
current position of certain parts of the top assembly to
J256.
J256 uses this information to control the actuators, and
thus, the operation of the top.

In a Hall sensor, a magnetic field acts perpendicular to the
direction of current flow in an electrical conductor resulting
in voltage differences. These voltage differences are converted to signals and utilized by Convertible Top Control
Module J256.
The distance between a Hall sensor and permanent magnet
is typically 0.1 in (3 mm).

The following Hall sensors react to the fields generated by
permanents magnets:
• Lower Convertible Top Compartment Enclosure Switch F520
• Left Convertible Top Closed Position Switch F411
• Right Convertible Top Closed Position Switch F412
• Convertible Top Compartment Cover -Closed- Switch F519
• Convertible Top Front Closed Position Switch F202
• Convertible Top Open Position Switch F171

Hall sensor
Permanent magnet

• Left Tensioning Bow Switch F408

These Hall sensors are referred to as monopolar or unipolar
Hall sensors. They react to the south pole of a permanent
magnet.

623_063

Switching distance

33

Upper Tensioning Bow Switch F408
Upper Tensioning Bow Switch F408 is a Hall-type sensor
installed on the long tensioning strut pivot arm on the left
hand side of the vehicle. A permanent magnet is attached
to the joint on the pivot arm.
When the tensioning arm reaches its upper position, F408
and the permanent magnet are facing one another. In this
position, Convertible Top Control Module J256 detects that
the tensioning strut is up.

Upper Tensioning Bow Switch F408

623_069

Lower Convertible Top Compartment Enclosure Switch F520
F520 is installed on the movable convertible top well at the
right hand side of the vehicle. It is a Hall sensor that detects
whether the movable convertible top well is in the lowered
position. The convertible top cannot be opened when the
movable convertible top well is in the upper position.
Handle

Movable convertible top well

The convertible top well has to be manually raised or lowered
by pulling or pushing on its handle. When the convertible top
is closed and the top well raised, an additional 1.4 cu ft (40
liters) of load capacity is available in the trunk and greater
access to the seat pass thru is available..
Lower Convertible Top Compartment Enclosure Switch F520

623_064

Left Convertible Top Closed Position Switch F411 and
Right Convertible Top Closed Position Switch F412
F411 and F412 are located on the left and right hand
convertible latch locks. They are both Hall sensors.

Convertible Top Locking Motor V223 engages and disengages the catch hooks on the convertible top. When the
catch hooks are engaged in the locks, each switch sends a
signal to the Convertible Top Control Module J256 indicating the top is closed.
Catch hook
Convertible Top Closed Position Switch

Permanent magnet
623_065

34

Convertible Top Compartment Cover -closed- Switch F519
F519 is located on Convertible Top Compartment Cover
Locking Motor V222. It is a Hall sensor.

A permanent magnet is attached to the striker. When the
convertible top box lid is closed, the magnet is directly
facing F519. Convertible Top Control Module J256 detects
that the top box lid is closed.

Striker on convertible
top compartment

Convertible Top
Compartment Cover
-closed- Switch F519

623_066

Convertible Top Front Closed Position Switch F202
F202 is installed in the direction of travel on the stationary
part of the main bearing bolted to the body on the left
hand side of the vehicle. It is a Hall sensor.

A permanent magnet is attached to the moving part of the
main bearing. If the magnet stops within the detection
range of the switch, Convertible Top Control Module J256
detects that the top is in the closed position.

Permanent magnet

623_067

Convertible Top Front Closed Position Switch F202

35

Convertible Top Open Position Switch F171
F171 is installed on the stationary part of the main bearing
on the left hand side of the vehicle. The switch is a Hall
sensor.

A permanent magnet is attached to the moving part of the
main bearing. If the magnet stops within the detection
range of the switch, Convertible Top Control Module J256
knows that the top is in its fully open position (stowed in
the convertible top compartment).

Permanent magnet

623_068

Convertible Top Open Position Switch F171

Convertible Top Compartment Cover Locking Motor V222
V222 locks the convertible top box lid. It is activated by
Convertible Top Control Module J256.

623_070

Convertible Top Compartment Cover Locking Motor V222

36

Convertible Top Compartment Latch -unlocked- Switch F293
and Convertible Top Compartment -locked- Switch F404
Both switches are integrated in Convertible Top Compartment Cover Locking Motor V222. These switches tell Convertible Top Control Module J256 whether the convertible
top box lid latch is engaged or disengaged.

Convertible Top Compartment Latch
-unlocked- Switch F293

The microswitches are actuated by tabs on the toothed
segment.
This switch tells Convertible Top Control Module J256
whether the convertible top box lid latch is engaged or
disengaged.

623_070

Convertible Top Compartment -locked- Switch F404

Trunk lid
The convertible top can only be operated when the trunk lid
is closed. When an opening or closing cycle is initiated,
Vehicle Electrical System Control Module J519 prevents the
trunk lid from being opened via the Release Button in the
Rear Lid Handle E234.

623_072

Switch for releasing the trunk lid

If a convertible top cycle is initiated when the trunk lid is
opened, a message is displayed in the DIS advising the
driver to close it.

Convertible top:
Please close
trunk lid

37

623_073

Convertible Top Hydraulic Pump V118
V118 includes:
•
•
•
•
•

Convertible Top Hydraulic Pump Relay J321
Convertible Top Hydraulic Pump Relay 2 J588
Power Convertible Top Valve 1 N272
Power Convertible Top Valve 2 N341
Power Convertible Top Valve 3 N342

The hydraulic pump together with the relays and valves
form a unit. The hydraulic pump is installed in the trunk,
behind the luggage compartment trim on the left-hand
side as seen in the direction of travel. The hydraulic pump is
housed in an acoustic enclosure which provides sound
insulation during pump operation.

623_074

Convertible Top Hydraulic Pump V118

Convertible Top Control Module J256 controls the hydraulic
pump via the two relays. The relays control the clockwise
and counter-clockwise operation of the pump.

relay. By switching the relay being operated, the direction
of the motor is controlled which in turn changes the direction of fluid flow from the pump.

This is done by operating only one of the two relays to
supply power to the pump. The non-operated relay supplies
the ground circuit for the pump via the 87a terminal on the

The valves guide the oil flow through the hydraulic lines
and into the hydraulic cylinders.

Power Convertible Top Valve 2
N341
Power Convertible Top Valve 1
N272
Power Convertible Top Valve 3
N342

Convertible Top Hydraulic
Pump Relay J321

623_118

Convertible Top Hydraulic
Pump Relay 2 J588
38

The hydraulic system is self-locking. This means that the
pressure generated by the pump is maintained within the
system for approximately 5 minutes. After 5 minutes, the
valves are de-energized and the hydraulic system de-pressurizes.
Collision of the convertible top and convertible top box lid

If the convertible top is in an intermediate position and the
hydraulic system de-pressurizes, the top will collapse
depending on its position. Also, the convertible top box lid
may close depending on its position.
In the worst case scenario, the convertible top will collide
with the convertible top box lid and may become damaged.
It may happen that neither the convertible top box lid nor
the convertible top reaches one of its limit positions. In
this case, it is no longer possible to operate the convertible
top because Convertible Top Control Module J256 receives
implausible signals. When this happens, the driver will be
alerted by a message in the DIS.

623_076

To continue operating the convertible top, the convertible
top box lid must be moved manually into a limit position.
The top cycle can then be resumed. If the limit position
was reached by opening the convertible top box lid, it must
be secured to prevent it from slamming shut.
The hydraulic system can also be de-pressurized by switching the ignition off and then push or pull the Power Top
Operation Switch E137 for approximately 5 seconds.

623_077

Power Top Operation Switch E137

39

Hydraulic cylinders
The convertible top and convertible top box lid are operated
by three pairs of hydraulic cylinders.
Two cylinders are responsible for operating the convertible
top box lid. Two are responsible for the tensioning strut
and two are responsible for the convertible top.

Cylinder pair for
tensioning strut

Cylinder pair for convertible top

Cylinder pair for
convertible top box
lid

623_078

The hydraulic cylinders operate in two working directions.

Compression stage

Hydraulic cylinder

Tension stage

Piston rod

623_079

Hydraulic connection

Hydraulic line

Hydraulic connection

Pistons

40

Lower Bracket Switch F517
F517 is integrated in the hydraulic cylinder responsible for
movement of the tensioning strut and is located on the left
hand side of the vehicle. It is a Hall sensor and can be
replaced separately from the cylinder.

When the tensioning strut is in its lowest position (tensioned), the cylinder is fully extended. The Hall sensor then
sends a signal to Convertible Top Control Module J256 that
the tensioning strut is down.

623_080

Lower Bracket Switch F517

Convertible Top Compartment -open- Switch F407
F407 is integrated in the left hand side hydraulic cylinder
responsible for movement of the convertible top box lid.
It is a Hall sensor and can be replaced separately from
the cylinder.

When the convertible top box lid is fully opened, the Hall
sensor sends a signal to Convertible Top Control Module J256.

623_081

F407 is attached to the cylinder

41

Hydraulic cylinders at main bearings
The two hydraulic cylinders responsible for the movement
of the convertible top are mounted at the main bearings.

623_082

Hydraulic cylinder of main bearing , (left hand side)

Convertible Top Control Module J256

Convertible Top Control Module J256
J256 controls and monitors each individual convertible top
operating cycle. It collects the information generated by
the sensors as well as information from other data bus
users. It evaluates and controls the actuators accordingly
and it communicates over the Convenience CAN.
J256 is located on the left hand side of the luggage compartment behind the trim cover for Convertible Top Hydraulic
Pump V118.

623_083

J256 is also responsible for system diagnostics. If implausible signals are detected or received at the wrong time, the
convertible top cycle is stopped and a DTC is recorded. A
warning message to the driver is also displayed in the DIS.

Convertible top:
malfunction!
You can continue driving

623_084
42

To protect Convertible Top Hydraulic Pump V118 from
being overloaded, its run-time is monitored by J256.
If the top has been running continuously for approximately
2 minutes and is closed by this time, J256 suppresses
further operation of the top for approximately 10 minutes.

The maximum continuous operation of the hydraulic pump
is limited to approximately 170 seconds at which time the
pump shuts off regardless of the top’s current position.
Further operation of the pump is subsequently suppressed
for approximately 20 minutes to prevent it from overheating. The driver is warned by a message in the DIS.
Convertible top:
no operation
possible

623_085

Convertible Top Locking Motor V223
V223 is attached to the front of the convertible top in the
middle. The motor uses a linkage to operate the two catch
hooks which lock the roof to the window frame.

623_086

Catch hook

43

Convertible Top
Locking Motor V223

Linkage

Convertible Top Latch -closed- Switch F295
Convertible Top Latch -closed- Switch F295 is integrated
with Convertible Top Locking Motor V223. It is a Hall
sensor type switch.

When V223 has locked the convertible top latches, a retaining plate is within the detection range of F295. This produces a “locked closed” signal which is sent to Convertible
Top Control Module J256.

Convertible Top Latch
-closed- Switch F295

Retaining plate

623_087

Convertible Top Latch -open- Switch F294
F294 is also integrated with Convertible Top Locking Motor
V223. It is a Hall sensor configured as an incremental
encoder or rotary encoder. It measures the number of
revolutions of V223.

Convertible Top Control Module J256 evaluates the signals
generated by the Hall sensor. When the corresponding
number of revolutions have been registered, J256 detects
“convertible top lock open.”

Convertible Top Latch -open- Switch F294

623_088

44

Emergency operation
In the event of a malfunction, the convertible top can be
closed manually. If possible this should be done by two
people.

Closing the convertible top

The emergency procedure cannot be done unless the
hydraulic system has been de-pressurized. The system
de-pressurizes automatically approximately 5 minutes after
the ignition is switched off. It can also be de-pressurized by
pushing or pulling Convertible Top Operation Switch E137
for approximately 5 seconds after the ignition has been
switched off.

•
•
•
•

!
!

Conditions:
Parking brake applied
All side windows lowered
Ignition switched off
Hydraulic system de-pressurized

The wheel bolt wrench from the vehicle tool kit is required