Convertible Top: Description and Operation
Fully Automatic Soft Top
Fully automatic soft top
As series standard, the MINI Convertible is equipped with a fully automatic, electrohydraulic soft top. It is operated by means of a button above the inside mirror. Opening and/or closing the soft top takes around 15 seconds (with side windows, approx. 18 seconds). A folding sun roof is integrated in the soft top. To open the soft top, the folding sun roof must first be fully opened. Pulling the button again opens the soft top.
Loading aid: Before setting down, the tensioning bar must be locked by hand on both sides.
Pulling the button for soft top operation towards the rear opens the folding sun roof first. Opening up to the maximum opening position is possible at a speed of up to 120 km/h. Above 120 km/h, the folding sun roof remains in the position it last assumed (until the vehicle has been moving slower than approx. 115 km/h for 2 seconds). The drive for the folding sunroof is arranged in the centre. Two bowden cables move the gates on the right and left.
If the button is operated again after opening the folding sun roof, all the windows are lowered simultaneously. The cowl panel is then unlocked and the soft top opened. The complete soft top is stored and locked in the stored state. The window are closed completely. Opening the soft top is possible at a speed of up to 30 km/h. Above this speed, the soft top movement is stopped. The instrument panel issues a Check Control message. The green LED starts to flash. As of a speed of 50 km/h, a fault memory entry is made. The soft top is moved by hydraulic cylinders. The are supplied with oil by a two-directional hydraulic pump across a short pressure line from the luggage compartment area. The reversal of the direction of rotation of the pump determines the direction of movement.
Brief component description
The following components are described for the fully automatic soft top:
Sensors for detection of the soft top position
In total, 5 Hall sensors, 1 micro-switch as well as 2 incremental transducer are installed as sensors for the Convertible Top Module (CTM).
- Hall effect sensors
The Hall sensors help the Convertible Top Module (CTM) to detect the position of the soft top. This means that after loss of terminal 30 or emergency actuation the soft top can still be operated without re-initialisation.
- 2 Incremental transducer in the cowl panel lock drive and folding sun roof
The incremental transducer is integrated in the locking drive and folding sun roof. The incremental transducers monitor the direction and speed of the drive.
- Microswitch, storage shelf down
This micro-switch ensures that the back shelf (= rear window shelf) is lowered. With the back shelf lowered, the micro-switch is short-circuited to earth. If this condition is not met, the soft top is not opened (block condition). In the event of a malfunction, the microswitch generates a fault entry.
NOTICE: No short circuit recognition.
A short circuit of the lead to the micro-switch is not detected by the Convertible Top Module (CTM).
CVM: Convertible-top module
The soft top Module (CVM) controls all the electric and hydraulic functions of the soft top. The convertible top module is connected on the K-CAN.
The soft top module is installed at the rollover protection.
Under certain block conditions, the CVM cannot execute a soft top movement (see 'System functions').
Soft top button
The button is integrated in the cowl panel in the roof operating unit. Pull button backwards: the soft top opens.
Push button forwards: the soft top closes. A green LED as function indicator is integrated in the roof control panel.
The LED only lights up with soft top movement, not with movement of the folding sun roof.
LED lights up:
- during soft top movement if no block condition is set
LED flashes:
- Soft top in a safe end position (a Check Control message also appears in the instrument cluster)
- Soft top in safe end position and one or a number of block conditions have been set (a yellow Check Control symbol also appears in the instrument cluster: e.g. back shelf not lowered or driving speed greater than 30 km/h)
Soft top drive
The soft top drive unit (motor with hydraulic pump and valve block) drives all soft top movements via cylinder pair. The cylinder pair moves the main pillars of the soft top.
The direction of movement of the soft top (OPEN to CLOSED) is controlled by 2 relays. The cylinders are supplied with oil by an hydraulic pump with 2 directions of rotation. The reversal of the direction of rotation of the hydraulic pump determines the direction of movement.
The hydraulic unit is safeguarded by a slow-acting 40-amp fuse. To protect the hydraulic unit, a 'Pump protection counter' is integrated in the soft top module (CVM).
The hydraulic pump only operates during the soft top movement. In the event of failure, emergency actuation is possible.
The hydraulic unit is installed in the rear left of the luggage compartment. The relays are also in the rear left of the luggage compartment.
Drive unit for lock and folding sunroof
An electric motor with gear locks and unlocks the soft top with cowl panel at the windshield frame. At the same time, this drive moves the folding sun roof. The Convertible Top Module (CTM) activates the drive.
The drive is arranged in the centre. The gates on the right and left are moved via 2 coiled cables, thus driving the folding sun roof. When the folding sun roof is open, the catches also open.
NOTICE: The drive has an additional function.
When the soft top is opened, the drive locks the stored soft top. The purpose of this function is crash locking. In the event of a crash, the stored soft top cannot fold forwards.
The following other control units are involved in the function of the soft top:
KOMBI2: auxiliary instrument
The auxiliary instrument (KOMBI2) delivers the ambient temperature (bus signal). The auxiliary instrument uses the Check Control symbol to show the Check Control messages relating to the soft top.
FRM: Footwell module
The footwell module (FRM) activates the front power windows. To open the soft top, the side windows must be lowered (bus signal from CVM).
JBE: Junction Box Electronics
The junction box electronics (JBE) deliver the signal as to whether the luggage compartment lid is closed (bus signal).
The power distribution box in the junction box supplies the soft top module (CVM) with electrical power (terminal 30g). In addition, the CVM is supplied by terminal 15 from the Car Access System (CAS). If, for example, the power supply from the junction box is interrupted, adequate communication with the BMW diagnosis system is still possible.
CAS: Car Access System
The CAS is the master control unit for the power windows. Following a request from the CVM, the CAS ensures that the side windows are opened or closed as the case may be. The CAS also prevents opening of the luggage compartment lid and any power windows movement with the soft top in an intermediate setting.
The Car Access System (CAS) controls convenience opening of the soft top. The signals from the remote key are received by the FBD receiver and directed to the CAS (not at present available for Comfort Access). Convenience opening and convenience closing via the lock cylinder in the driver's door: the CAS receives the signal from the footwell module (FRM).
System functions
The following system functions are described for the automatic soft top:
- Opening and closing the soft top
- Conditions for opening and closing
- Pump protection counter
- Overheating protection for drive lock and folding sun roof
- Soft top opening duration display
- Check Control messages
Opening and closing the soft top
Conditions for opening and closing
Pump protection counter
A pump protection counter has been implemented to fully safeguard the hydraulic pump. The pump safeguard is active and the function inhibited after an operation time of 3.5 minutes. A ramp function enables an initial shortened operating period after 1.1 minutes. The full operating time of 3.5 minutes is available after a waiting period of 15.5 minutes.
When the pump protection is active, a fault is entered in the fault memory.
Overheating protection for drive lock and folding sun roof
The function is inhibited after an operation time of more than 2.20 minutes. The full operating time is available after a waiting period of 50 seconds. It is always possible to close the soft top. When the overheating protection is active, a fault is entered in the fault memory.
Soft top opening duration display
The convertible top opening duration display is on the left beside the rev counter on the steering column. The display is only activated if the Soft Top is opened. Counting only starts when the Soft Top is fully opened and only if the engine is running. Two digital counters can be called up in the on-board computer display. The four-digit counter can be reset using the trip distance reset button. The six-digit counter can only be reset by means of a corresponding diagnosis instruction.
The soft top opening duration display shows hours and minutes. An LED is activated each hour on the hour. Minutes are displayed by the pointer on a scale of 0 to 60. A maximum of 7 hours can be displayed (6 LEDs and one pointer revolution). Following this, the display is reset automatically and the display cycle starts again from the beginning. The switch to a new display cycle is indicated by the flashing LEDs.
The display is also reset when the four-digit resettable counter overruns. In this case, the display cycle starts again from the beginning after only 2 hours (1 LED and one pointer revolution). The special feature of this is that 98 hours can be displayed in 14 cycles with a respective duration of 7 hours. The remaining difference to the overrun corresponds to these 2 hours.
Check Control messages
It is not possible to open and close the soft top in certain situations. Corresponding Check Control messages are displayed in the instrument panel for this purpose. On vehicles with a central information display (CID), a text message is displayed together with a supplementary set of instructions.
A Check Control message is displayed every 5 seconds.
Notes for Service department
General notes
NOTICE: Emergency actuation, see repair instructions.
The emergency actuation is described in detail in the repair instructions.
NOTICE: Zero-maintenance hydraulic fluid.
The hydraulic fluid does not have to be changed because the system is filled with life-time fluid. If, as a result of a leak, hydraulic fluid needs to be topped up, always use the approved grade of hydraulic fluid. Pour in hydraulic fluid only up to marking on oil reservoir.
NOTICE: If excessive noise is generated, bleed the hydraulic system.
If excessive noise is generated while the hardtop is moving, the hardtop must be opened and closed several times. This will automatically bleed the hydraulic system in the oil reservoir.
Diagnosis instructions
IMPORTANT: When working on the rollover protection system, open the soft top.
If the BMW diagnosis system triggers the rollover protection, the soft top must be opened first of all. Otherwise, the soft top will be destroyed.Mechanical triggering is not possible on the R57.
Notes on encoding/programming
After replacement, the soft top Module (CVM) must be encoded again.
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.