Soft top, function

P77.30-2593-79

Function requirements, general

 Transport mode not activated (as of 01.06.2012)

 No overvoltage or undervoltage

 When the transport mode is activated, it is no longer possible to open a closed soft top.

Electrohydraulic soft top, general

The soft top is opened and closed electro-hydraulically.

The electric motor in the soft top control hydraulic unit actuates the hydraulic pump, which generates the required operating pressure. The control is performed by the rear control unit.

The soft top can be operated via the soft top actuation switch or the "Comfort opening/closing via infrared" function.

The rear control unit reads in the corresponding request, evaluates the input signals of all limit switches and actuates the electric motor and the solenoid valves in the soft top control hydraulic unit. The soft top can be opened and closed via the hydraulic cylinder.

When the soft top is opened or closed, components with high switch-on current are actuated. However, to ensure operation of the soft top (without switch-off due to undervoltage), the rear control unit actuates these components with a time offset (t = 80 ms).

Emergency operation:

If the soft top cannot be closed automatically (e.g. roll bar extended), the soft top can later be closed or locked manually.

The following conditions must be fulfilled here:

 Side window open

 Rear head restraints lowered

 Pressure relieved in soft top control hydraulic unit with Allen wrench (included in owner's manual folder)

 Soft top compartment hinges folded over and straps (contained in vehicle tool kit) pulled through

 Trunk lid closed

Open soft top manually:

 Pull soft top compartment lid toward rear to vertical stop with straps.

 Guide soft top out of soft top compartment and position against windshield frame.

 Remove cap from Allen screw in headliner.

 Turn valve clockwise with Allen wrench to stop and then counterclockwise to stop.

 Position soft top bow in vertical position and lower soft top compartment lid.

 Press soft top bow downward until it arrests.

The soft top control comprises the following partial functions:

 Function sequence for opening/closing soft top

 Function sequence for soft top stop mode

 Function sequence for overload protection

 Function sequence for centrally closing side window

 Function sequence for soft top indicator and warning messages

 Function sequence for comfort open driving (with CODE 288 (AIRCAP))

P77.30-2489-80

Additional function requirements for opening/closing soft top

 No engine start (circuit 50 Off)

 Status of stop top recognized

 Luggage compartment separation closed

 Trunk lid closed

 Speed v < 40 km/h

 Rear head restraints lowered

 Roll bar not actuated (defined over rear head restraint position)

 The electronic ignition lock control unit sends the 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 partition (open or closed) is sensed by the variable soft top limit switch. The rear control unit directly reads in the status of variable soft top limit switch.
The status of the trunk lid (open or closed) is sensed by the trunk lid rotary tumbler switch in the trunk lid central locking motor. The rear SAM control unit directly reads in the status of the trunk lid rotary tumbler switch and transmits it to the rear control unit over the interior CAN.
The instrument cluster sends information on the vehicle speed via interior CAN to the rear control unit.
The position of the rear head restraints (lowered or extended) is defined by the lower head restraint limit switches. The rear control unit directly reads in the status of the lower head restraint limit switches.

Function sequence for opening/closing soft top

Opening and closing the soft top via the soft top control switch is only possible with circuit 15 ON.

The electronic ignition lock control unit sends the circuit 15 status over the interior CAN to the rear control unit. 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 via infrared, the soft top is opened or closed for the time the request is present. The left front door control unit transmits the information "Convenience feature mode" and "Direction of convenience feature mode" to the rear control unit via the interior CAN.

Before opening or closing the soft top, the rear control unit should determine the soft top position (open, closed or valid intermediate position) ( search). The position search is started after reading in the actuation request. To define the momentary position of the soft top, the rear control unit evaluates the signals of all limit switches. If no plausible position is recognized, the soft top operation is interrupted (e.g. active actuation is not performed).

When the soft top is opened, first the front side windows are lowered completely to the short stroke position and then the rear side windows. Then the soft top is unlocked on the crossmember above the windshield.

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 actuate the front door power window motors. The rear power window motors are actuated directly by the rear control unit. Hall sensors are integrated into the power window motors. Their signals indicate the position of the side windows. The front door control units transmit the information "Short stroke position actuated" to the rear control unit via the interior CAN. The rear control unit evaluates the signals from the hall sensors integrated into the rear power window motors.

 Model 207.4
with code 494 (US version)
All four side windows are lowered completely.

When the side windows are lowered, the rear control unit actuates the electric motor in the soft top hydraulic unit. The hydraulic pump driven by the electric motor, generates the required operating pressure for the further motion of the soft top. Now the rear control unit actuates the solenoid valves in the soft top hydraulic unit directly, allowing oil flowing into the individual hydraulic cylinders. All totaled seven hydraulic cylinders are installed. Two soft top bow hydraulic cylinders (raising/lowering), soft top compartment lid hydraulic cylinder (opening/closing), soft top control hydraulic cylinder and soft top lock hydraulic cylinder each.

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. Then the rear window is put back down and the soft top released at the upper windshield frame. Then the soft top is folded down toward rear over the passenger compartment and stored in the rear. Finally the soft top compartment lid is closed.

During the soft top operation, the message "Soft top in operation" is displayed in the multifunction display. When opening faster than v < 40 km/h, the rear control unit stops the motion. The message "Soft top completely open/closed" is displayed in the multifunction display of the instrument cluster.

During closing the function sequence is opposite. The front side windows are lowered completely to the short stroke position and then the rear side windows. Then the soft top compartment lid is opened and the soft top is folded up from the rear toward the front, unfolded over the passenger compartment and locked 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). Finally, the side windows are closed (except on vehicles with CODE 494 (USA version)).

When the soft top is completely closed, all four side windows are closed again (except on vehicles with code 494 (USA version)). On vehicles with code 494 (USA version), the side windows are not closed automatically.

The movement is monitored by the rear control unit by evaluating the signals from the limit switches. If the soft top is not properly locked and the vehicle is standing still a warning message appears in the instrument cluster. When driving, an additional warning tone is output.

 The hydraulic cylinders in question remain activated for a short time even after reaching the individual end positions (defined over the signals from the limit switches) in order to compensate for tolerances in the switching points of the limit switches.

 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 soft top stop mode

 Soft top not in locked end position

Function sequence for soft top stop mode

If the opening or closing procedure of the soft top it 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 soft top mechanism can no longer move. 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 the stop mode is active, a warning message ("Completely open/close soft top") appears on the multifunction display in the instrument cluster.

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

 Circuit 15 ON for t = 7 min

 Circuit 15 OFF for t = 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.

If the stop mode is interrupted, the rear control unit transmits the request to output a warning t = 15 s to the instrument cluster via the interior CAN before the first solenoid is switched off. The message "Soft top lowers" appears in the multifunction display in the instrument cluster. In addition, a warning tone is sounded. If all solenoid valves are switched off after t = 5 s the rear control unit rescinds the request to output a warning tone.

If a new request is recognized and the position search made by the rear control unit is successful, all solenoid valves are switched off and the motion of the soft top is continued starting at the fixed position. The opening and closing procedure of the soft top is interrupted when a speed of v = 40 km/h is exceeded, so that the soft top cannot be damaged by aerodynamic drag.

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

Function sequence for overload protection

The unlocked soft top can be opened or closed in either directions as long as the temperature of hydraulic oil does not exceed T = 85 °C. The temperature sensor in the hydraulic unit electric motor actuates the overload protection of the soft top control hydraulic unit electric motor when the motor is thermally overloaded. 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 T < 75 °C

 Inhibit/interruption T > 85 °C

Close soft top:

 Enable T < 85 °C

 Inhibit/interruption T > 90 °C

The outside temperature is included in the calculation of the hydraulic oil temperature. 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.

Error evaluation of rear control unit at outside temperature of T < -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

Error evaluation of rear control unit at outside temperature of T < -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.

Function sequence for centrally closing side window

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 actuate the front door power window motors. The rear door control unit directly actuates the rear power window motors.

Function sequence for soft top indicator and warning messages

The rear control unit evaluates the functionability of the soft top control continuously.

Malfunction is indicated in the multifunction display. For this purpose the rear control unit transmits the corresponding information to the instrument cluster via the interior 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.

When the soft top is locked and is moved faster than v = 8 km/h, an additional warning message "Soft top locked" appears in the form of a red warning gong. Output of this warning is limited to t = 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 t = 20 s. Actuation is started t = 15 minute before deactivating the stop mode.

Additional function requirements for comfort open driving (only with code 288 (AIRCAP))

 Terminal 15 ON

 Soft top completely open

 Speed < 160 km/h (for operation)

 The wind deflector can be retracted or extended above the windshield and the draft stop between the rear head restraints up to a speed of v = 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.

Function sequence for comfort open driving (with CODE 288 (AIRCAP))

When using the wind deflector and draft stop, the eddy currents (draft) in the passenger compartment is reduced.

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.

Up to 31.05.2013:

The rear control unit directly reads in the status of the draft stop and wind deflector button and actuates the wind deflector actuator motor and head restraint drive actuator motor in the rear.

As of 01.06.2013:

The rear control unit directly reads in the status of the draft stop and wind deflector button and actuates the head restraint drive actuator motor in the rear. As of a speed of v > 40 km/h the wind deflector also extends beyond the windshield. At a speed oft v < 15 km/h the wind deflector retracts automatically. The rear control unit actuates the wind deflector actuator motor.

The status of the wind deflector and draft stop (extended or retracted) is signaled to the driver by two status LEDs in the draft stop and wind deflector button, which are directly actuated by the rear control unit.

The draft stop can be extended or retracted together with the head restraints in the rear by actuating the rear head restraint button. The overhead control panel control unit (with transmission 711, 716) or the lower left control panel (with transmission 722.9, 725) transmits the status of the rear head restraint button via the instrument LIN, front SAM control unit and interior CAN to the rear control unit. The rear control unit then actuates the head restraint drive actuator motor in the rear.

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.

 For cleaning the wind deflector can be extended when the soft top is closed. For this purpose the parking brake must be applied. Then the net of the wind deflector can be cleaned.
The status of the parking brake is detected through the parking brake indicator switch. The front SAM control unit reads in the status of the parking brake indicator switch directly and sends it over the interior CAN to the rear control unit.

 If a seatbelt is applied in the rear, the rear head restraints and the draft stop move to the upper-most position.