Soft Top, Function - GF77.30-P-0002LF
Model 217.4
Function requirements, general
- Transport mode not activated
- No overvoltage or undervoltage
When the transport mode is activated, it is no longer possible to open a closed soft top.
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.
All totaled seven hydraulic cylinders are installed. Two soft top bow hydraulic cylinders (raising/lowering), soft top compartment lid hydraulic cylinder (opening/closing), two soft top control hydraulic cylinders and one soft top lock hydraulic cylinder each.
Ten limit switches are installed all totaled. 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) (Comfort opening/closing function)
Emergency operation
The soft top can be manually (by hand) opened and closed.
Close soft top manually:
- Open side window.
- Bleed pressure in hydraulic unit using Allen wrench (included in Operator's Manual pouch).
- Fold over soft top compartment hinges and pull through straps (included in vehicle tool kit)
- Close trunk lid.
- Close and lock soft top
Manually open soft top:
- Pull soft top compartment lid using straps to rear, until the vertical end stop is reached.
- Route soft top out of soft top compartment and place onto windshield frame.
- Remove cap from Allen screw in headliner.
- Turn valve clockwise using Allen wrench up to end stop, and then turn in counterclockwise direction.
- 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 manually opening/closing trunk partition
- Function sequence for stop mode
- Function sequence for overload protection
- Function sequence for centrally closing side window
- Function sequence for displaying control and warning messages
- Function sequence for extending/retracting wind deflector and draft stop
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
- Speed v < 40 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/liftgate 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.
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.
Function sequence for 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.
Trunk partition:
The trunk partition separates the stowage space for the open soft top from the remaining trunk. The trunk partition motor activates a lever which moves the trunk partition upward (to open) and downward (to close).
The position of trunk partition is sensed by the following Hall sensors:
- Left trunk partition Hall sensor
- Right trunk partition Hall sensor
- Trunk partition open/closed Hall sensor
The rear control unit directly reads in the signals from the Hall sensors and evaluates them. Before opening soft top, the position of the trunk partition is checked. If the trunk partition is moved upward (open), it is lowered to the end position (closed). For this purpose the rear control unit directly actuates the trunk partition motor.
Power transmission between the lever on the trunk partition and the drive is monitored by the hall sensor trunk partition power transmission drive. The rear control unit directly reads in the signals from the Hall sensors. If, when closing the trunk partition, an interruption in the power transmission is sensed (e.g. luggage being pinched), the trunk partition is reversed and returns to the upper end position.
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 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 electric motor generates the operating pressure required for 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 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.
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 lid is opened and the soft top is then folded up from the rear toward the front, unfolded over the passenger compartment and locked 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 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)). On vehicles with CODE 494 (USA version), the side windows are not closed automatically.
During the soft top operation, the message "Soft top in operation" is displayed in the instrument cluster. If when opening, the vehicle is driving at a speed in excess of v = 40 km/h, the rear control unit stops any 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 manually opening/closing trunk partition
- Trunk lid opened
- Soft top closed and locked (to open trunk partition)
Function sequence for manually opening/closing trunk partition
The trunk partition can be opened or closed manually by actuating the trunk partition switch. The rear control unit reads in the status of the trunk partition switch directly and actuates the trunk partition motor according to the actuation.
Additional function requirements for stop mode
- Soft top not in locked end position
Function sequence for 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 is 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 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 has been interrupted, the rear control unit transmits the request to output a warning via the interior CAN, electronic ignition lock control unit and CAN user interface to the instrument cluster t = 15 s before the first solenoid valve is switched off. The message "Soft top lowers" appears in the instrument cluster. A warning gong sound in addition. 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 = 4 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 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 at T < 75°C
- Inhibit/interruption T > 85°C
Close soft top:
- Enable at T < 85°C
- Inhibit/interruption at 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 then actuate the front power window motors. The rear door control unit directly actuates the rear power window motors.
Function sequence for 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.
| Priority | Fault/operation | Symbol | Display text | Warning gong |
|---|---|---|---|---|
| 1 | Soft top unlocked and speed signal v > 8 km/h | Soft top | Soft top locked (red) | Yes |
| 2 | Opening or closing operation active over soft top control switch (active until soft top is locked and pump shut off) | Soft top | Soft top in operation (white) | No |
| 2 | Stop mode active | Soft top | Completely open/close soft top (white) | No |
| 2 | Stop mode is active and switched off in t = 15 s | Soft top | Soft top lowers (white) | Warning gong active for t = 20 s |
| 3 | Soft top operation not possible during driving, speed signal > 40 km/h | Soft top | Reduce speed to 40 km/h (white) | Yes |
| 4 | Soft top operation not possible because trunk partition not closed | Arrow on closed trunk lid | Close trunk partition (white) | Yes |
| 5 | Soft top operation not possible, because trunk lid is not closed | Vehicle with open trunk lid | Symbol only, no text (white) | Yes |
| 6 | Soft top operation not possible because temperature on soft top control hydraulic unit is too high or voltage too low with engine running | Soft top | Soft top in operation, please wait (white) | Yes |
| 7 | Soft top operation not possible because voltage too low with engine OFF | Soft top | Start engine (white) | Yes |
| 8 | Soft top operation not possible due to error in rear control unit or in periphery (on all errors preventing a soft top operation) | Soft top | Soft top, visit workshop (white) | Yes |
When the car is driven at a speed greater than 8 km/h with the soft top unlocked, a warning gong sounds in addition to the warning message "Lock soft top" on the display. 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 extending/retracting wind deflector and draft stop
- 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 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 extending/retracting wind deflector and draft stop
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.
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. 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 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 by two status LEDs in the draft stop and wind deflector button, which are directly actuated by the rear control unit. 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.
If a seat belt is applied in the rear, the draft stop moves to the uppermost position.
| Electrical function schematic for opening/closing soft top with switch | PE77.39-P-2054-97SEA | ||
| Overview of system components for soft top, component description | GF77.30-P-9997LF |