Hard Top: Description and Operation
Retractable hardtop
A retractable hardtop is being used on the new BMW 3-Series E93 convertible for the first time. The three-part roof construction has been manufacture from sheet steel plate using the lightweight construction method. The roof opens in approx. 22 seconds and closes in approx. 23 seconds.
The retractable hardtop provides the following advantages:
- A high degree of on-road comfort with the roof closed with increased suitability for daily use
- Good all-round view with the roof closed on account of the narrow C-pillar as well as large rear window
- Opening and closing with a total height of 170 centimetres, which means it is also possible in garages
A central hydraulic unit drives the retractable hardtop, The sequence of movements is supported by 8 hydraulic cylinders. 6 gas-pressurized props are also involved in the sequence of movements. The hydraulic unit is activated by the Convertible Top Module (CTM). A total of 14 sensors monitor the sequence of movements.
IMPORTANT: Emergency backup operation exclusively for service use.
Emergency actuation of the retractable hardtop for the customer is not implemented. However, emergency actuation is possible in Service. The emergency actuation is described in detail in the repair instructions.
Brief component description
The following components are described for the retractable hardtop:
Micro-switch on the retractable hardtop
A total of 5 micro-switches deliver a signal to the Convertible Top Module (CTM):
- Cowl-panel microswitch made (1)
This micro-switch is fitted in the vehicle in the cowl panel to the left. When the guide bolt of the front roof shell has reached the cowl panel, the micro-switch is opened. From this position onwards, the drive for the hardtop interlock is activated. The roof shells are locked.
- Micro-switch cowl panel unlocked (2)
This micro-switch is installed to the left below the drive for the hardtop retainer. The contacts of the micro-switch are opened when the catches are fully locked. The retaining hooks can be locked at the cowl panel as well as on the base plate in the luggage compartment. When the hardtop is fully closed, the contacts of the micro-switch are open (high signal). When the hardtop is opened, the catches are unlocked and the contacts of the micro-switch are closed. The retaining hooks on the baseplate lock once the roof package is deposited in the luggage compartment. The microswitch contacts open during this process.
- Cowl panel microswitch locked (3)
This micro-switch is installed to the right below the drive for the hardtop retainer. The contacts of the micro-switch are closed when the catches on the cowl panel are fully locked. When a high signal is received by the CTM, opening of the catches of the hardtop is concluded. The retainers of the front roof shell to the middle roof shell and of all three roof shells are detached. When thereafter the roof shells are moved one on top of the other and placed in the luggage compartment, the contacts of the micro-switch remain opened. It is only when the catches start to lock that the contacts of the microswitch are closed again.
- Coupling lock microswitch on right side closed (4), Coupling lock microswitch on left side closed (5)
There are microswitches on the left-hand and right-hand cylinders for the interlocking ring buckle. These microswitches deliver a signal to the CTM when the interlocking ring buckle is locked.
Hall sensors on the retractable hardtop
A total of 9 Hall sensors deliver a signal to the Convertible Top Module (CTM):
- Hall-effect sensor for roof shells partially open (1), Hall-effect sensor for roof shells partially closed (2)
Two Hall sensors are attached to the right-hand cylinder for the roof shells; these pick up the motion of the piston in the cylinder. When the piston is extended the Hall-effect sensor for partially open roof shells transmits a message to the CTM. In this position, the roof shells are completely one on top of the other. Now the roof package can be deposited in the luggage compartment. The Hall-effect sensor for partially-closed roof shells transmits a signal to the CTM when the piston in the roof shell cylinder is almost completely retracted. As of this position and until the cowl panel is reached, the hardtop closes more slowly (indirect anti-trapping mechanism).
- Hall-effect sensor coupling lock on right open (3)
This Hall sensor is located at the right-hand cylinder for the interlocking ring buckle. The Hall sensor delivers a signal to the CTM when the piston is fully extended. In this position the locking mechanism of the rear module and the rear roof shell with the body is released.
- Hall-effect sensor for rear module closed (4)
This Hall sensor is installed on the front right of the main bearing. The Hall sensor delivers a signal to the CTM when the rear module has reached the lowest position. There is a bracket on the rear module that triggers the signal when the end position is reached.
- Hall-effect sensor roof package stored (5)
This Hall sensor is installed on the right-hand base plate in the luggage compartment. The Hall sensor delivers a signal to the CTM when the guide bolt of the front roof shell has reached the guide in the base plate. As of this position, the drive for hardtop locking can be activated and the rear module closed again.
- Hall-effect sensor rear module opened (6), Hall-effect sensor rear module almost closed (7)
Two Hall-effect sensors that register the movement of the piston in the rear module's cylinder are installed on the right-side cylinder for the rear module. When the piston is extended, a signal is sent to the CTM. In this position, the rear module is fully opened. The roof package can be stored in the luggage compartment or raised from the luggage compartment. The Hall-effect sensor for the almost-closed position transmits a signal to the CTM as soon as the piston is almost completely retracted in the cylinder. As of this position and until the end position is reached, the rear module closes more slowly.
- Hall-effect sensor for luggage compartment partition (8)
The Hall sensor for the luggage compartment partition reports that the luggage compartment partition is in the lower position. This means that an important condition for the function has been met. If this signal fails, the hardtop cannot be stored (closing is possible). The Hall sensor is installed on the lefthand rear module bearing.
- Hall-effect sensor for roof package erected (9)
A Hall-effect sensor is installed on the right main pillar (cylinder); this sensor transmits a signal to the CTM once the piston is retracted in the cylinder. The roof shells are erected when the cylinders are retracted.
Button for operation
The button is in the centre console between the controller and armrest. The button for the retractable hardtop works in a similar way to a power window switch.
- Pulling and holding the button opens the retractable hardtop and the side windows.
- Pushing and holding the button closes the retractable hardtop and the side windows.
If the button is released during the movement, the motion of the retractable hardtop or side windows stops immediately. The function display on the button has 2 LEDs (red and green). The green LED remains lit during the opening and closing processes. The red LED indicates incorrect operation or incorrect conditions (e.g. luggage compartment partition has not been lowered). The red LED flashes when the hardtop is in an intermediate position provided that no user control entries are being made at the same time. Flashing does not indicate a fault. The flashing LED is intended to draw attention to the fact that the vehicle must not be driven in this state.
CTM: Convertible top module
The Convertible Top Module (CTM) is the central control unit for all functions of the retractable hardtop. The CTM is fitted on the right on the partition. The CTM controls the retractable hardtop, the rear module and the Soft Close Automatic system. The CTM controls the drive for hardtop locking. The CTM also controls the hydraulic pump and the 8 hydraulic cylinders via the 5 valves in the hydraulic unit. The CTM is connected by the K-CAN to other control units. In this way, e.g., information on the outside temperature, driving speed and status of the luggage compartment lid is received via K-CAN. On opening and/or closing the hardtop, the CTM sends a signal to the Car Access System (CAS). The CAS serves as the master controller for the electric power windows. The CAS sends CAN signals to activate the footwell module (FRM) as well as the junction box electronics (JBE). The signal serves as a command to lower the front and rear side windows. Under specific conditions the customer will receive messages in the form of Check Control reports in the instrument cluster.
Depending upon whether the roof is open or closed: The CTM transmits a signal to the Diversity aerial requesting aerial changeover.
Drive for hardtop locking
The roof shells of the hardtop are interlocked. The front roof shell is also locked at the cowl panel by 2 catches. An electric motor in the front roof shell acts as the drive.
The electric motor powers the spiral cables on the left and right sides (similar to arrangement with tilt sunroof). There are locking pins at the end of the coiled cables; these are pushed by the front roof shell into the middle roof shell. This locks these roof shells. Simultaneously a linkage mechanism locks the centre with the rear roof shell.
The retaining hooks on the cowl panel are locked. The middle engaging hook is also locked.
NOTE: The locking hooks and locking pins have been deleted.
The locking hook between the front roof shell and the centre roof shell was dropped in 2007. The locking pins connecting the centre roof shell to the rear roof shell were deleted in 2009.
Hydraulic unit
The hydraulic unit is located in a recess in the luggage compartment floor. The corresponding valve positions and direction of rotation of the hydraulic pump determine the direction of movement of the hardtop and of the rear module. The direction of rotation of the hydraulic pump is controlled by 2 relays. The hydraulic pump generates an operating pressure of 150 to 200 bar.
In order to prevent the hydraulic pump from overheating if the hardtop is operated frequently, the temperature in the hydraulic pump is measured. The temperature sensor is connected to the CTM by 2 wires without earth. A break in wiring leads to a fault code memory entry. As of 90 °C, a closing movement of the hardtop that has already started is continued up to the safe end position. At 105 °C, the movement of the hardtop is stopped immediately. When the temperature falls below 90 °C , the movement can be continued.
KOMBI: Instrument panel
The instrument cluster delivers the outside temperature (bus signal).
FRM: Footwell module
The footwell module (FRM) controls the front electric power windows. To open the hardtop, the side windows must be lowered (bus signal from CTM).
JBE: Junction Box Electronics
The junction box electronics unit (JBE) controls the rear electric power windows. To open the hardtop, the side windows must be lowered (bus signal from CTM).
The junction box electronics deliver the signal as to whether the luggage compartment lid is closed (bus signal). The power distribution box in the junction box supplies the convertible-top module (CTM) with power from Terminal 30g. In addition, the CTM is supplied with terminal 15 by 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.
Aerial diversity
Depending on whether the roof is closed or opened, the CTM sends a signal to the aerial diversity. The aerial diversity then changes over the aerials accordingly.
System function
The following system functions are described for the retractable hardtop:
- Functional networking
- Opening and closing the retractable hardtop
- Convenient operation and convenient loading
- Check Control messages
- Automatic soft-close
Functional networking
The overview of functions shows the operating networks of the control units involved in the processes.
Opening and closing the retractable hardtop
To open and close the retractable hardtop, the following conditions must be met:
- terminal R is ON
- Outside temperature above --12 °C
- Tailgate (rear module) closed
- Vehicle stationary (driving speed 0 kph)
- Luggage compartment partition lowered
- Lateral inclination of the vehicle less than 11 °
- Electric power windows have been initialised
- Battery voltage greater than 11.5 volts
- Fewer than 5 opening and closing operations in succession
- Temperature of the hydraulic fluid for opening maximum 90 °C and for closing maximum 105 °C
IMPORTANT: Special charactreristic of control button.
The fault code A6A4 is stored under the following conditions:
- Terminal R On while the button is pressed
- After concluded roof movement, button pressed for longer than 20 seconds
The fault code is stored as "not present". The roof is temporarily inoperative. After opening once using the button, the roof is operative again.
When the button in the centre console is pulled, the conditions are checked by the Convertible Top Module (CTM). The side windows are lowered following successful testing. At the same time, the front roof shell is unlocked at the cowl panel and the roof shells themselves are unlocked. Activating the hydraulic components unlocks the interlocking ring buckle (fastener for rear roof shell and rear module to body). The 3 roof shells are now moved one on top of the other. Then the rear module is opened and the roof package is stored. The stored roof package is then locked (similar to the way it is at the cowl panel). The rear module is then closed and locked. Finally, the side windows are raised to their top position (European version only).
The hardtop closes in reverse order. When the button in the centre console is pulled, the conditions are checked by the Convertible Top Module (CTM). Following a successful check the side windows may be lowered (green LED lights up). The rear module is unlocked and opened. Simultaneously, the roof package is also unlocked. When the rear module is fully opened, the roof package is set up. When the roof package has reached its end position, the rear module is closed, locked by the interlocking ring buckle and then unlocked again. Now the roof shells are moved apart until the front roof shell reaches the cowl panel. Now the roof shells themselves are locked and the front roof shell is locked at the cowl panel. Finally, the rear roof shell and the rear module are locked with the body. The green LED in the button goes out. If the button remains pressed, the side windows move upwards.
Convenient operation and convenience function for loading and unloading the luggage compartment
The retractable hardtop can be operated using the remote control as well as the mechanical key in the door lock. In the case of vehicles with the "Comfort Access" optional equipment, the hardtop can be opened and closed using the identification sensor.
The new convenience function for loading and unloading enables rapid access to the luggage compartment when the roof is open, e.g. when large items of luggage are loaded. The convenience function is activated as follows:
- Briefly press the luggage compartment button on the remote control
- Then press and hold down the luggage compartment button (no more than 1 second may elapse between releasing and pressing again)
First of all, the rear module is unlocked and completely opened. Then the roof package is swung out of the luggage compartment up to an intermediate position. Subsequently, the rear module is closed and locked. The luggage compartment lid is unlocked via the Soft Close Automatic system. Here, the luggage compartment lid opens slightly.
The convenience functions via the remote control are country-specific.
Conditions for using remote control and ID transmitter with Comfort Access (SA322)
Check Control messages
In certain situations, it is not possible to open or close the hardtop. The corresponding messages are displayed in the instrument cluster as Check Control messages. On vehicles with a Central Information Display (CID), the short text and supplementary information are displayed.
The Check Control messages serve to explain in closer detail the red LED on the button which lights up in the event of a fault. A Check Control message is displayed every 5 seconds.
Automatic soft-close
For convenient closing of the luggage compartment lid, the Soft Close Automatic system is installed as series standard. The Soft Close Automatic system consists of 2 drives. The drives lock the luggage compartment lid on the left and right at the support member of the rear module. This increases the stability of the rear end.
NOTE: Cable and lock barrel have been discontinued.
The cable and the lock barrel were deleted in 2010. This means that it is no longer possible to unlock the tailgate manually.
When the luggage compartment locks on the left and right have reached the locking bracket, 2 micro switches are pressed. The signals are sent to the junction box electronics (JBE). The Convertible Top Module (CTM) receives the signals across the CAN bus. The CTM then activates both drive units for the Automatic Soft Close system, continuing until the tailgate is locked.
Banging the luggage compartment lid shut would make closing with the Soft Close Automatic system unnecessary. For reasons relevant to safety, it must be ensured that the luggage compartment lid really is closed.
This is why the drives of the Soft Close Automatic system are activated in all cases.
Both drives have an anti-repeat circuit to prevent overheating. The anti-repeat circuit permits up to 20 activations of the Soft Close Automatic system (counter up to 20 increments). Thereafter, the Soft Close Automatic system is electrically blocked for approx. 2 minutes.
Notes for Service department
General notes
IMPORTANT: Emergency backup operation exclusively for service use.
Emergency actuation of the retractable hardtop for the customer is not implemented. However, emergency actuation is possible in Service. The emergency actuation is described in detail in the repair instructions.
IMPORTANT: Vehicle must be stationary.
It is not possible to open or close the retractable hardtop while the vehicle is being driven. Due to the high power consumption of the retractable hardtop of up to 40 amperes, the hardtop may only be operated with a battery charger connected or with the engine running. Comply with the additional information in the Owner's Handbook.
IMPORTANT: No finger-protection feature is installed on the rear power windows.
The rear electric power windows are not equipped with a finger-protection feature. This means there is no toll function for closing the rear windows either.
NOTE: No convenience closing using outside door handle electronics!
On vehicles with Comfort Access, convenience closing is not possible using the outside door handle electronics. Convenience closing is run via lock cylinders.
NOTE: 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 fluid reservoir.
NOTE: 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.
NOTE: The hardtop weighs roughly 98 kilogrammes!
At least two persons and appropriate lifting equipment are required (refer to repair instructions).
Diagnosis instructions
IMPORTANT: Open the hardtop before performing service operations on the roll-over protection system.
If the diagnosis system deploys the rollover protection the first response should be to open the hardtop. Otherwise the rear window will be destroyed. This also applies to manual deployment.
IMPORTANT: Special characteristic of control button.
The fault code A6A4 is stored under the following conditions:
- Terminal R on when pressure is applied to the button
- After concluded roof movement, button pressed for longer than 20 seconds
The fault code is stored as "not present". The roof is temporarily inoperative. After opening once using the button, the roof is operative again.
Special instructions for code entry and programming
The Convertible Top Module (CTM) must be recoded following replacement.
National market versions
Bear in mind the different national versions for the convenience functions: see section "Convenient operation and convenience function for loading and unloading the luggage compartment". Not responsible for printing errors, mistakes and technical changes.