GF77.30-P-0002CA Soft Top, Function
GF77.30-P-0002CA Soft Top, Function
Function requirements, electrohydraulic soft top, general
- Electric soft top control functioning properly
- No engine start (circuit 50 OFF)
- No overvoltage or undervoltage
- Trunk lid closed (status signal from rear SAM control unit with fuse and relay module (N10/2)
- Trunk partition (variable soft top compartment) closed
- Soft top status recognized (plausible detection of soft top position with limit switches)
- Temperature of soft top mechanism hydraulic unit (A7/5) in valid range for corresponding actuation direction and type of actuation.
- Soft top actuators (solenoid valves in soft top control hydraulic unit (A7/5) and cylinders) OK
- Speed signal < 40 km/h
- Roll bar not actuated.
- Rear head restraints moved down (limit switch signal)
The wheel speed required for calculation of the actual vehicle speed is transmitted to the rear control unit (N22/6) via the interior CAN (CAN B) by the electronic stability program control unit (N30/4) (vehicles without code (233) DISTRONIC PLUS) or electronic stability program Premium control unit (N30/7) (vehicles with code (233) DISTRONIC PLUS). The instrument cluster (A1) also transmits the indicated vehicle speed to the rear control unit.
If the rear head restraints, the draft stop and wind deflector (only on vehicles with code (288) AIRCAP) are not down, they are automatically moved down. If the trunk partition is not closed, it must be closed by hand.
When the roll bars are extended, the head restraints cannot be lowered.
Function description, electrohydraulic soft top system, general
This system allows the soft top to be opened and closed automatically. The function sequence is based on an electrohydraulic combination. The soft top is controlled electrically and the opening and closing procedure is supported hydraulically. The rear control unit (N22/6) forms the central unit in the electrohydraulic soft top system, receiving, transmitting and relaying signals. The signals are transmitted via the interior CAN (CAN B) or transmitted or received directly.
Actuation possibilities
As a matter of principle a differentiation is made between the following two possibilities for actuating the electrohydraulic soft top system:
- Opening/closing soft top with soft top control switch (S84)
- Comfort opening/closing for soft top with transmitter key (A8/1) (driver side only)
For safety reasons the opening operation is interrupted immediately (stop mode function) anytime the soft top control switch or the button on the transmitter key is released.
Warning signals
The following warning signals are present for the soft top function:
- When driving without the soft top locked properly, a warning signal sounds for 10 s and a warning message appears in the instrument cluster A1)
- Warning and control messages in instrument cluster (A1) on operating states and fault messages
A reset is required before the warning signal can be output again.
Partial functions
The electrohydraulic soft top allows the following subfunctions:
- Soft top opening/closing function(with soft top control switch)
- Soft top comfort opening/closing with transmitter key
- Rear control unit search function
- Monitoring of soft top functions
- Electrohydraulic soft top stop mode
- Subsequent soft top locking
- Automatic raising/lowering of power windows depending on soft top control
- Central window closing function
- Overload protection function upon exceeding temperature limits for soft top control hydraulic unit (A7/5)
- Soft top emergency actuation
- Comfort opening when driving (only with code (288) AIRCAP)
Described in separate subfunction
- Soft top indicator and warning messages, function
General interrupt conditions
- Overvoltage or undervoltage
- Cancellation of actuation request
- Through abort conditions resulting from sequence
- Motor start (c. 50)
- Trunk lid open
- Speed signal > 40 km/h
- Trunk partition open
- Soft top actuators (soft top control hydraulic unit (A7/5) and cylinders) OK
- Soft top control hydraulic unit (A7/5) temperature too high
- Failure of message to interior CAN (CAN B) for longer than 50 ms
Soft top opening/closing function(with soft top control switch)
Additional function requirements
- Circuit 15 On
- Soft top status recognized (detection of soft top position)
These function requirements are checked during the entire soft top sequence, opening or closing. If one of these function requirements is no longer satisfied or if a CAN message is absent for > 50 ms, the soft top sequence is interrupted immediately.
It is no longer possible to release the trunk lid, until the soft top has opened or closed completely.
Function
When the soft top control switch (S84) is actuated and held down, the soft top is opened or closed.
The actuation request to open or close from the soft top control switch is read in directly by the rear control unit. The side windows are opened and closed together with the soft top. This means that when the soft top is opened, the side windows are opened first, and then the soft top itself is opened. This defined sequence for the side windows and soft top, prevents damage resulting from collisions when the soft top is actuated. The rear control unit (N22/6) relays the signal to open or close the side windows over the interior CAN (CAN B) to the left front door control unit (N69/1) and right front door control unit (N69/2) to actuate the left front door power window motor (M10/3) and right front door power window motor (M10/4).
The left rear power window motor (M10/5) and right rear power window motor (M10/6) are actuated directly by the rear SAM control unit. The rear control unit actuates the soft top control hydraulic unit (A7/5) for opening and closing the soft top.
During the soft top opening operation, the soft top compartment lid first moves to the rear, releasing the rear section 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 back over the vehicle passenger compartment and stowed in the rear. Finally the soft top compartment lid is closed. During the opening and closing operation the message "Soft top in motion" appears in the instrument cluster (A1) until the soft top is arrested in the corresponding end position. During closing the function sequence is opposite. After opening the side windows and raising the soft top compartment cover out of the rear end, the soft top is moved toward the front and arrested at the upper windshield frame. 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 section of the soft top is moved back toward the rear and soft top compartment lid slides toward the front, locking the rear section of the soft top (soft top bow). Finally the side windows are closed (not on USA version, code (494)). The opening and closing operation is monitored by the rear control unit using various limit switched (see control unit description). If the soft top is not properly locked and the vehicle is standing still a warning message appears in the instrument cluster. If the soft top is not properly locked when driving a warning tone also sounds.
Additional termination requirements.
- C. 15 OFF
With Code (494) USA version, the side windows can only be closed with the power window switches or the power window central control switch (S84s5), not with the soft top control switch or the transmitter key.
For this reason it is necessary to roll up the side windows with the power window central control switch or the power window switches after closing the soft top.
Hydraulic opening and closing
A pump in the soft top actuation hydraulic unit (A7/5) generates the required operating pressure for the hydraulic cylinders to actuate the soft top mechanism. A total of 7 hydraulic cylinders are installed:
- Soft top locking hydraulic cylinder (1 each)
- Soft top bow hydraulic cylinder (raise/lower)(2 each)
- Soft top compartment lid hydraulic cylinder (open/close) (2 each)
- Soft top actuation hydraulic cylinder (2 each)
The soft top system is controlled by the rear control unit (N22/6). It evaluates the positions of the limit switches and control switches and switches the soft top control hydraulic unit solenoid valves accordingly.
The hydraulic cylinders in question remain activated for a short time even after reaching the individual limit switch positions in order to compensate for tolerances in the switching points of the limit switches.
Chronologically offset actuation of actuators
Since actuators with high switch-on currents are actuated for operation of the soft top, it is necessary for the rear control unit (N22/6) to actuate the actuators specified below with a chronological offset (80 ms).
The actuators to be considered are:
- Actuator motor for rear head restraint drive (M28/14)
- Left rear power window motor (M10/3)
- Right rear power window motor (M10/4)
- Left rear power window motor (M10/5)
- Right rear power window motor (M10/6)
- Soft top control hydraulic unit (A7/5)
Soft top comfort opening/closing with transmitter key
Additional function requirements
- C. 15 C off (key not inserted in ignition lock)
- Soft top status recognized (detection of soft top position)
It is no longer possible to release the trunk lid, until the soft top has opened or closed completely.
The soft top comfort opening/closing functions with the transmitter key are described in detail in the separate function description of the "Convenience feature".
Function
Comfort closing or opening of the soft top is activated with the transmitter key (A8/1) via the infrared signal.
For this purpose press and hold down the appropriate button, "open" or "close" on the transmitter key while aiming it at the infrared remote control receiver for the driver side front door (A26/1). The left front door control unit (N69/1) (on vehicles with left-hand steering) or right front door control unit (N69/2) (on vehicles with right-hand steering) receiver the signal from the infrared remote control receiver for the driver side front door and relay it over the interior CAN (CAN B) to the electronic ignition switch control unit (N73).
The electronic ignition switch control unit checks the transmitter key's access authorization. If the access authorization is valid the electronic ignition switch control unit relays the "open or close" signal to the rear control unit (N22/6). The remaining sequence corresponds to that when opening or closing with the soft top control switch.
Additional termination requirements.
- Circuit 15 ON
Rear control unit search function
The search function is started when an actuation request for the soft top is received. The rear control unit recognizes the position of the soft top via the search function. For this purpose all limit switches are read in directly and the and status of the trunk lid rotary tumbler switch (M14/7s1) is read in over the interior CAN. This determines whether the soft top is opened, closed or in a valid intermediate position. If a plausible position of the soft top is not recognized, the soft top operation is stopped and a corresponding warning message appears in the instrument cluster (A1).
Monitoring of soft top functions
The soft top motion sequence is monitored by checking the solenoid valve actuation time (except for the stop function) required to reach the expected limit switch positions.
When the required time is exceeded, the procedure is interrupted and a fault stored in the rear control unit.
Electrohydraulic soft top stop mode
Additional function requirements
- Soft top not in locked end position
The soft top opening or closing operation is interrupted immediately (stop mode function), when one of the following situations is present:
- Soft top control switch (S84) or button on transmitter key released (stop function) or
- the trunk lid is opened or
- the vehicle speed is greater than 40 km/h.
Function
If the actuation request for the soft top operation is interrupted due to erroneous or incorrect input values, the Stop mode is actuated.
During the stop mode the solenoid valves for the soft top control hydraulic unit are actuated so that all soft top motion is stopped and the soft top is arrested.
If the "Open or close soft top" operation is reenabled and another actuation request is present, the soft top operation is started or continued.
As soon as the stop mode is active, a warning message ("Completely open/close soft top") appears on the display in 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 sequence of the rear control unit is not enabled, the Stop mode is reactuated when it receives an actuation request and the stop time is automatically increased:
- Circuit 15 ON for 7 min.
- Circuit 15 OFF for 15 s
If the stop mode is discontinued 15 s before the first solenoid valve is switched off, a request is output to the instrument cluster over the interior CAN to sound the warning gong and display the warning message "Soft top lowering". The request for the warning gong is canceled 5 s after all solenoid valves have switched off.
If a new request is recognized and the rear control unit search function was successful, all stop mode solenoid valves are switched off and the soft top operation is continued in the sequence step found.
If the soft top system is in the stop mode and the vehicle is moving at a speed greater than approx. 4 km/h, actuation of the hydraulic cylinders is canceled to prevent any of the soft top components from being damaged by the high force of the wind resistance.
If a solenoid valve responsible for the stop mode function is defective, the stop mode is not started.
Subsequent soft top locking
Additional function requirements
- C.15 ON (over soft top control switch)
or
- C. 15R OFF (over transmitter key)
In contrast to "normal" soft top actuation, the following requirements are not important for subsequent locking:
- Power window error/power window positions
- Vehicle speed signals
Function
If the soft top is not completely locked following actuation, the "Subsequent locking" function can be activated, whereby here, in contrast to the regular soft top sequence only the soft top control hydraulic unit is actuated not the power windows.
Automatic raising/lowering of power windows depending on soft top control
Additional function requirements
- Soft top sequence active
Function
When the soft top is opened or closed (not on Code (494) USA version), the windows are actuated to prevent damage resulting from operation of the soft top. The soft top can be actuated by pressing the soft top control switch or the transmitter key. The rear control unit has the master function and therefore the highest priority correspondingly. The left front power window motor (M10/3) is actuated by the left front door control unit (N69/1) and the right front power window motor (M10/4) is actuated by the right front door control unit (N69/2).
The left rear power window motor (M10/5) and right rear power window motor (M10/6) are actuated directly by the rear SAM control unit. Desmodromic valve control of the side windows corresponds to manual actuation.
Additional termination requirements
- Blockage detection
With Code (494) USA version, the side windows can only be closed with the power window switches or the power window central control switch, not with the soft top control switch or the transmitter key.
Central window closing function
Additional function requirements
- Circuit 5R On
Function
The"central window closing function" allows all four power windows to be controlled centrally by actuating the central power window switch (S84s5).
Actuation of the central power window switch "UP" to the first catch, closes the windows until the central power window switch is released. Pulling the central power window switch beyond the first catch to the stop, causes the side windows to roll up all the way automatically. The rear control unit (N22/6) has the master function and therefore the highest priority correspondingly. The left front power window motor is actuated by the left front door control unit and the right front power window motor is actuated by the right front door control unit.
The left rear power window motor and the right rear power window motor are actuated directly by the rear control unit.
Additional termination requirements
- Blockage detection
Overload protection function upon exceeding temperature limits for soft top control hydraulic unit (A7/5)
It is possible to actuate the unlocked soft top in both operating directions until a hydraulic oil temperature of 85 °C is exceeded. The temperature sensor (A7/5b1) in the soft top control hydraulic unit (A7/5) actuates the overload protection when the motor is thermally overloaded. The temperature sensor signal is read in from the rear control unit (N22/6) directly.
Hydraulic oil temperatures in °C:
Open soft top from closed non-actuated state:
Enable < 75 °C
Disable/Interrupt > 85°C
Close soft top:
Enable < 85 °C
Disable/Interrupt > 90°C
Moreover, the outdoor temperature is considered when checking the soft top for failure. The outside temperature is measured by the outside temperature sensor (B14) and read in by the front SAM control unit with fuse and relay module (N10/1). This transfers the message to the rear control unit over the interior CAN (CAN B).
Error consideration of rear control unit at outside temperatures less than minus 15 °C:
- No fault in temperature sensor (A7/5b1) for soft top control hydraulic unit (A7/5)
- Not displayed in instrument cluster (A1) in event of timeout errors
- Not saved in event of time-out errors
Error consideration of rear control unit at outside temperatures less than minus 15 °C:
- Errors are stored
- Displays in instrument cluster (A1) are activated
Soft top emergency actuation
If the soft top cannot be closed automatically, it is possible to possible to subsequently close and lock it by hand with the emergency actuation.
The soft top emergency actuation is described in detail in the individual steps in the operating instructions. Always observe these instructions when using the soft top emergency actuation.
If the rear head restraints cannot be lowered, the roll bar may be actuated (indicated in instrument cluster (A1)). If the roll bar is actuated, the rear head restraints cannot be lowered and the soft top cannot be opened or closed. It is then necessary to operating it manually.
Basic requirements:
- Side windows open
- Head restraints lowered
- Pressure relieved in soft top control hydraulic unit (A7/5) 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
Close soft top:
- 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 socket on soft top lock (in covering in front of headliner).
- Turn 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.
Comfort opening when driving (only with code (288) AIRCAP)
Additional function requirements, driving position
- Circuit 15 On
- Soft top completely open
- Wind deflector actuator motor (M96/2)
- Actuator motor for rear head restraint drive (M28/14) functioning properly
- Speed signal < 160 km/h (for operation)
The wind deflector can be extended and retracted up to a speed of 160 km/h. However when the speed threshold is exceeded the wind deflector remains extended or retracted and can be moved (extended or retracted) again only after dropping below the speed threshold.
Driving position
The wind deflector and draft stop button (S84s4) allows the wind deflector actuator motor to extend the wind statically over the windshield and the rear head restraint drive actuator motor to extend the draft stop with the head restraints. This results in less turbulence in the air in the vehicle interior and a reduction of the airstream acting on the passengers. The rear control unit (N22/6) actuates the wind deflector actuator motor and rear head restraint actuator motor directly. Two status LED's in the wind deflector and draft stop button provide feedback for the driver.
The rear head restrain button (N72/1s4) on the upper control panel (N72/1) allows the draft stop to be extended together with the rear head restraints. For this purpose the upper control panel send a request over the instrument panel LIN (LIN 1) to the front SAM control unit with fuse and relay module; the front SAM control unit with fuse and relay module then sends the request to the rear control unit over the interior CAN.
Additional function requirements for cleaning position with soft top closed
- Circuit 15 On
- Soft top completely closed
- Parking brake operated
- Wind deflector actuator motor (M96/2)
The status of the parking brake is received by the rear control unit via the interior CAN by the front SAM control unit with fuse and relay module, which directly reads in the parking brake indicator switch (S12)
Cleaning position with soft top closed
In the cleaning position it is only possible to extend the wind deflector over the windshield. This is indicted by the left status LED for the draft stop and wind deflector button.
