Soft Top, Function - GF77.30-P-0002RF

Model 205.4 

Courtesy of MERCEDES-BENZ USA

Function requirements, general 

• Transport mode not activated
• No overvoltage or undervoltage

When the transport mode is activated, the closed soft top cannot be opened.

Soft top in general 

The soft top is operated electrohydraulically by actuating hydraulic cylinders.

An electric motor in the soft top control hydraulic unit actuates a hydraulic pump, which generates the required operating pressure.

The hydraulic cylinders are controlled by the rear control unit through solenoid valves in the soft top control hydraulic unit.

A total of six hydraulic cylinders are installed. Two soft top bow hydraulic cylinders (raising/lowering), two soft top compartment lid hydraulic cylinders (opening/closing) and two soft top control hydraulic cylinders. Twelve limit switches are installed in total. They monitor the position of the soft top, soft top bow, soft top compartment lid and soft top lock. The status of the limit switch is read in directly by the rear control unit.

Control points: 

• Soft top control switch
• Transmitter key (A8/1) (Convenience opening/closing function)

Emergency actuation: The soft top can be opened and closed manually.

The soft top control comprises the following partial functions:

• Opening/closing soft top 
• Close remaining luggage compartment separator (with code 4U9 (semiautomatic remaining luggage compartment separator)) 
• Stop mode 
• Overload protection 
• Automatic closing of side windows 
• Displaying control and warning messages 
• Extend/retract wind deflector and draft stop (with code 288 (Draft stop for convertible)) 

Additional function requirements for opening/closing soft top 

• No engine start (circuit 50 Off)
• Circuit 15 ON (for control point switch for soft top control)
• Soft top in defined position
• Trunk lid closed
• Remaining luggage compartment separator closed
• Speed below 60 km/h
• Roll bar not triggered

The electronic ignition lock control unit sends the circuit 15 and circuit 50 status over the interior CAN to the rear control unit.

The position of the soft top is sensed by evaluating the status of all limit switches. The rear control unit directly reads in the status of all limit switches.

The status of the trunk lid (open or closed) is sensed by the trunk lid lock main catch switch in the trunk lid lock. The rear SAM control unit directly reads in the status of the trunk lid lock main catch switch and sends this via the interior CAN to the rear control unit.

The rear control unit directly reads in the signals from the trunk partition closed Hall sensors.

Information on the vehicle speed is sent by the instrument cluster via the user interface CAN, electronic ignition lock control unit, and interior CAN to the rear control unit.

The Supplemental Restraint System control unit transmits the status of the roll bar to the rear control unit via the user interface CAN, electronic ignition lock control unit and interior CAN.

Opening/closing soft top 

When the soft top control switch is actuated, the soft top is opened or closed manually for the time the request is present. The rear control unit directly reads in the status of the soft top control switch.

When the "Comfort opening/closing" function is actuated using the transmitter key, the soft top is opened or closed as long as the request is pending.

Remaining luggage compartment separator: 

The remaining luggage compartment separator separates the stowage space for the soft top from the rest of the trunk.

Depending on the vehicle equipment, two variants of the remaining luggage compartment separator are available:

• Manual remaining luggage compartment separator: The remaining luggage compartment separator is moved by hand.
• Semiautomatic remaining luggage compartment separator (with code 4U9 (semiautomatic remaining luggage compartment separator)): The remaining luggage compartment separator is closed by the trunk separator electric motor at the push of a button.

If the soft top is opened, the remaining luggage compartment separator must be closed so that the folded soft top its into the provided stowage space. If large or bulky objects prevent the complete closing of the remaining luggage compartment separator, the open soft top cannot be placed in the trunk. The trunk separator closed Hall sensor senses the closed state of the remaining luggage compartment separator.

Open soft top procedure: 

• The front side windows are lowered to the short stroke position.

  The rear control unit transmits the request "Actuate short stroke position" to the front door control unit via the interior CAN. The front door control units then actuate the front power window motors. Hall sensors are integrated into the front power window motors, and their signals enable the position of the front side windows to be determined. The front door control units transmit the information "Short stroke position actuated" to the rear control unit via the interior CAN.

• The rear side windows are lowered completely.

  The rear power window motors are actuated directly by the rear control unit. Hall sensors are integrated into the rear power window motors, and their signals are used to determine the position of the rear side windows.

• Movement of the soft top is started.

  The rear control unit directly actuates the front soft top lock motor to open the soft top lock. The rear control unit directly actuates soft top control hydraulic unit electric motor. The hydraulic pump driven by the soft top control hydraulic unit electric motor generates the operating pressure required for the movement. The rear control unit then actuates the solenoid valves in the soft top hydraulic unit directly, allowing oil to flow into the individual hydraulic cylinders.

• The soft top compartment lid moves toward rear and thereby unlocks the rear part of the soft top (soft top bow). Then the rear section of the soft top with the rear window rises so that the soft top compartment lid can open.
• The rear window is put down again and the soft top released at the upper windshield frame.
• The soft top is folded together over the passenger compartment and stowed in the rear end.
• The soft top compartment lid is closed again.

  The corresponding hydraulic cylinder remains actuated for a short time even after the individual end positions are reached (defined via the signals of the limit switches). As a result, the tolerances of the switch points of the limit switches are adjusted.

Close soft top procedure: 

• The front side windows are lowered to the short stroke position.
• The rear side windows are lowered completely.
• The soft top compartment cover is opened and the soft top is raised up from the rear toward to the front. The soft top then unfolds over the passenger compartment and locks at the upper frame of the windshield.
• Then the soft top with rear window is raised in the rear area, so that the soft top compartment lid can close.
• After closing the soft top compartment lid, the rear area of the soft top pivots toward the rear. The soft top compartment lid moves toward front and locks the rear section of the soft top (soft top bow).
• The front and rear side windows are closed again (except for vehicles with CODE 494 (USA version)).

During the soft top operation, the message "Soft top in operation" is displayed in the instrument cluster. If during opening, the vehicle speed is above 60 km/h, the rear control unit stops the movement. The instrument cluster's multifunction display shows the message "Completely open/close soft top". The rear control unit transmits the request to display a corresponding message via the interior CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster.

The rear control unit monitors the movement of the soft top. For this purpose it checks the actuation time of the solenoid valves for each movement (except in the stop mode) until the input signals from the limit switches are received. If the stored time is exceeded, the actuation is interrupted and a fault is stored in the rear control unit.

If the soft top is not completely locked, it can be locked later by a new operation request. The side windows are not completely closed in this case.

If the side windows were closed previously by hand, they only move to the short stroke position. Only when the soft top closed, all side windows are closed completely.

Additional function requirements for closing the remaining luggage compartment separator (with code 4U9 (semiautomatic remaining luggage compartment separator)) 

• Trunk lid opened

Close remaining luggage compartment separator (with code 4U9 (semiautomatic remaining luggage compartment separator)) 

The remaining luggage compartment separator can be closed by activating the trunk separator switch. The rear control unit directly reads in the status of the trunk separator switch and actuates the trunk separator electric motor accordingly.

The trunk separator electric motor folds the panel with the remaining luggage compartment separator roller blind toward the rear. This procedure tensions the remaining luggage compartment separator and the roller blind and shaft is pulled downward with the remaining luggage compartment separator roller blind. The stowage space for the soft top is enabled. The lower end position (remaining luggage compartment separator closed) is sensed by the trunk separator Hall sensor. The trunk separator Hall sensors located at the sides detect when the remaining luggage compartment separator hits obstacles when closing. The rear control unit directly reads in the signals from the trunk partition Hall sensors and evaluates them.

Additional function requirements for stop mode 

• Soft top not in locked end position

Stop mode 

If the opening or closing procedure of the soft top is interrupted due to erroneous or missing input factors, the rear control unit activates the stop mode. During the stop mode the solenoid valves for the soft top control hydraulic unit are actuated so that the motion of the soft top is stopped. The soft top is arrested. When the opening or closing procedure of the soft top if enabled and a new actuation request is present, it is restarted or continued.

As soon as stop mode is active, a warning message ("Completely open/close soft top") appears on the instrument cluster.

When the stop mode is active, the soft top is arrested when:

• Circuit 15 ON for 7 min
• Circuit 15 off for 15 s

If the opening and closing procedure of the soft top is not yet enabled, the stop mode is reactivated after a new request is received.

When the stop mode is interrupted, the rear control unit sends a request to issue a warning 15 s prior to the shutoff of the first solenoid valve via interior CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster. The message "Soft top lowers" appears in the instrument cluster. A warning gong sound in addition. If all solenoid valves are switched off after 5 s the rear control unit rescinds the request to output a warning tone.

If a request is detected again and the position search of the rear control unit was successful, all solenoid valves are deactivated. The soft top movement is continued from the fixed position. The soft top opening or closing process is canceled if a speed of 4 km/h is exceeded. This is so that the soft top is not damaged due to aerodynamic drag.

If a solenoid valve responsible for stop mode function is defective, the stop mode is not started.

Overload protection 

Opening and closing the soft top is possible even when a hydraulic oil temperature of 85°C is exceeded. The temperature sensor in the soft top control hydraulic unit actuates the overload protection of the soft top control hydraulic unit electric motor. The rear control unit directly reads in the signal from the temperature sensor and calculates the hydraulic oil temperature.

Hydraulic oil temperatures in °C:

Open soft top from closed non-actuated state:

• Enable below 75°C
• Inhibit/interruption above 85°C

Close soft top:

• Enable at below 85°C
• Blocking/interruption at above 90°C

The outside temperature is included in the calculation. The outside temperature is recorded by the outside temperature sensor. The front SAM control unit directly reads in the signal from the outside temperature sensor and calculates the outside temperature. Then the SAM control unit transmits the value for the outside temperature to the rear control unit via the interior CAN.

Possible sources of error of the rear control unit at an outside temperature below -15°C:

• No fault in temperature sensor for soft top control hydraulic unit
• Not displayed in instrument cluster in event of timeout errors
• Not saved in event of time-out errors

Possible sources of error of the rear control unit at an outside temperature above -15°C:

• Errors are stored
• Displays in instrument cluster are activated

Additional function requirements for side window central closing 

• Circuit 15R ON

The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the rear control unit.

Automatic closing of side windows 

All side windows can be closed from one control unit via the power window central operation switch.

If the power window central operation switch is actuated to the first catch, the power window motors are actuated for the time the actuation is in progress. The side windows are closed. When the power window central operation switch is actuated beyond the first catch, the power window motors are actuated until the side windows are completely closed.

The rear control unit reads in the status of the power window central operation switch directly and transmits the information "Comfort actuation mode" and "Comfort actuation direction" to the front door control unit via the interior CAN. The front door control units then actuate the front power window motors. The rear door control unit directly actuates the rear power window motors.

Displaying control and warning messages 

The rear control unit evaluates the functional capability of the soft top control continuously.

Malfunctions are displayed in the instrument cluster. For this purpose the driver rear control unit sends the corresponding information to the instrument cluster via interior CAN, electronic ignition lock control unit and user interface CAN.

The message is displayed regardless of the circuit status of circuit 15. Also during comfort opening/closing of the soft top.

Individual messages can be transmitted parallel to other messages. Otherwise, the rear control unit transmits only one message to the instrument cluster with the corresponding priority. Messages with same priority cannot be present simultaneously due to the soft top motion sequence.

If the vehicle is driven faster than 8 km/h when the soft top is locked, a warning gong sounds in addition to the warning message "Lock soft top" in red lettering. Output of this warning message is limited to 10 s. Then the output of a warning gong is inhibited and is only armed by:

• Circuit 15 OFF changes to circuit 15 ON
• Position change of soft top
• Soft top control switch actuated in opposite direction, relocking
• Relocking (after soft top control switch changes from "actuated" to "not actuated")

The warning gong is also actuated when the stop mode is deactivated for 20 s. Actuation starts 15 s before deactivating the stop mode.

Additional function requirements for extending/retracting wind deflector and draft stop (with code 288 (Draft stop for convertible)) 

• Terminal 15 ON
• Soft top completely open
• Speed below 160 km/h (for operation)

Extending and retracting the wind deflector via the windshield and draft stop is possible up to a speed of 160 km/h. Above this speed threshold, the wind deflector and the draft stop remain in the previous position.

The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the rear control unit.

The instrument cluster sends information on the vehicle speed via interior CAN to the rear control unit.

Extend/retract wind deflector and draft stop (with code 288 (Draft stop for convertible)) 

When using the wind deflector and the draft stop, the eddy (draft) is reduced in the vehicle interior.

Retracting and extending the wind deflector and draft stop, can be operated over the draft stop and wind deflector button in the soft top control switch.

The rear control unit reads in the status of the draft stop and wind deflector button directly, and actuates the draft stop actuator motor accordingly. Starting at a speed of 40 km/h the wind deflector above the windshield also extends. It automatically retracts again at a speed below 15 km/h. The rear control unit actuates the wind deflector actuator motor.

The position of the draft top and the wind deflector is monitored by the limit switch, which is integrated in the corresponding actuator motor. The rear control unit directly reads in the signals of the limit switches.

The status of the wind deflector and draft stop (extended or retracted) is signaled to the driver via two status LEDs in the draft stop and wind deflector button. The rear control unit directly actuates the status LED in the draft stop button and wind deflector.

If the wind deflector and draft stop is extended and circuit 15C is switched off, the wind deflector and draft stop retract (component protection). After switching on circuit 15, the wind deflector and draft stop is extended. If the draft stop and wind deflector button is pressed shortly after the circuit 15C is switched off, the draft stop button extends again.

Model 205.4 as of 12/3/18

To relieve the draft stop after retracting, the draft stop actuator motor is actuated in the opposite direction for a short time (reversed).

For cleaning the wind deflector can be extended when the soft top is closed. For this purpose the parking brake must be applied.

If a seat belt is applied in the rear, the draft stop moves to the uppermost position.