The boot lid/tailgate is opened and closed by means of the boot lid/tailgate lift. Opening is triggered by operating the BOOT button in the vehicle interior or by means of a button on the remote control (FBD). The opened boot lid/tailgate can be closed by operating the button inside the boot lid/tailgate and by pressing the button for the boot lid/tailgate on the remote control (FBD not USA).
Closing and opening the boot lid/tailgate are by means of a hydraulic system fitted on the boot lid/tailgate. The hydraulic system is activated via the boot lid/tailgate lift control unit. There is also an automatic soft-close facility (SCA) and an electrical rear lid release on the boot lid/tailgate.
The boot lid/tailgate lift works together with the Car Access System (CAS) and power module (PM). The boot lid/tailgate lift has diagnostic capability. Exchange of information to the diagnosis tester is across the K-CAN PERIPHERIE data bus.
The boot lid/tailgate lift controls the opening and closing of the boot lid/tailgate. The boot lid / tailgate button is connected to the boot lid/tailgate lift (inside the boot lid/tailgate).
The power module (PM) monitors the operating status and the open-circuit current consumption of the vehicle. The power module (PM) also controls the boot lid lock and the soft-close automatic (SCA) for the boot lid/tailgate. Information is received and sent via the K-CAN PERIPHERALS data bus.
The Car Access System (CAS) contains the function of the radio remote control, the ignition switch, the terminal control and the immobiliser. The Car Access System (CAS) is the gateway module between the data buses K-CAN SYSTEM and K-CAN PERIPHERALS.
The BOOT button (S8) in the vehicle interior is read in via the Car Access System (CAS). The data telegrams are transferred across the K-CAN PERIPHERIE data bus.
The boot lid/tailgate can be opened by pressing the BOOT button (S8) on the interior front light unit on the headlining.
The opened boot lid/tailgate can only be closed using the button (S117) in the boot lid/tailgate. The close function is triggered by touching the button (S117). During the closing operation, the boot lid/tailgate can be halted and then set in motion once again. The boot lid / tailgate movement can also be initiated when the boot lid/tailgate is half open. The boot lid/tailgate is always moved to an end position (lid opened or closed). In the end position, the drive is automatically switched off.
The direction of movement of the opened boot lid/tailgate changes with every second press of the button (S117):
Button pressed: locking -> stop, button pressed: opening -> stop, etc. The time for opening and closing can be coded.
The boot lid/tailgate can also be opened via the remote control (FBD) and its movement can be stopped. By briefly pressing the button (<1.6 seconds) on the remote control (FBD), the boot lid/tailgate is opened or its movement is stopped.
Continuous pressure (>1.6 seconds) on the button for the boot lid/tailgate on the remote control (FBD) closes the boot lid/tailgate as long as the button is pressed (not USA). Releasing the button cancels the closing operation and the boot lid/tailgate is opened again for 1 second. The time for opening and closing can be coded.
A linear sensor on the pressure cylinder is used to detect the boot lid / tailgate position. The linear sensor outputs a voltage value that corresponds to the boot lid / tailgate position.
The hydraulic pump creates the pressure required in the hydraulic system for the boot lid / tailgate movement. The hydraulic pump is driven by a reversible electric motor. The motor direction is changed by means of a switching relay. A PWM circuit keeps the motor speed constant across the entire voltage range in the vehicle electrical system.
The hydraulic valve controls the pressure between the hydraulic pump and hydraulic cylinder. The hydraulic valve is controlled by the boot lid/tailgate lift.
The maximum pressure is set up at the hydraulic cylinder if the hydraulic valve is supplied with current (valve closed). Only a low pressure is built up in the hydraulic cylinder when no power is applied to the relay valve (valve open).
The release drive unlocks the mechanical boot lid / tailgate lock. The release drive is fitted in the boot lid/tailgate and is activated by the power module (PM). The release drive incorporates the rear lid contact, which signals to the power module (PM) the position of the rear lid lock.
The SCA drive is installed in the body. The SCA drive incorporates a position switch, which records the position of the SCA drive. The SCA drive is controlled by the power module (PM).
After operation of the hotel switch, the hotel setting is engaged. In the hotel setting, the button for opening the boot lid/tailgate is deactivated on the remote control. The BOOT (S8) button on the front interior light unit on the headlining is also deactivated. The boot lid/tailgate also remains locked when the vehicle is unlocked. The hotel switch is fitted in the upper glovebox beneath the switch for setting the clock.
When the vehicle is unlocked, the boot lid/tailgate can be operated using the BOOT button and the remote control. When the vehicle is secured, the boot lid/tailgate can only be opened using the remote control.
After activating the open command, first the boot lid / tailgate lock is unlocked via the release drive. If the power module (PM) is informed by the boot-lid contact that the lock is open (boot-lid contact switches to earth), the drive for the Soft Close Automatic (SCA) is activated towards 'open'. The drive for automatic Soft Close is active until top dead centre is reached and the position switch in the drive connects to ground.
At the same time as activation of the drive for automatic Soft Close, the power module (PM) transmits the information ”boot lid / tailgate lock unlocked” via the K-CAN data bus to the boot lid/tailgate lift. The boot lid/tailgate lift then supplies the hydraulic valve and the hydraulic pump with current and the boot lid/tailgate is opened.
Via the linear sensor, the boot lid/tailgate lift detects the position of the boot lid/tailgate. Shortly before the position ”boot lid/tailgate opened” is reached, the speed of movement is reduced and the boot lid/tailgate moves slowly into the end position.
If the button is pressed again during the opening procedure, the operation is interrupted. If the button is then pressed again, the closing operation is carried out.
To close the boot lid/tailgate, the direction of rotation of the hydraulic pump electric motor is changed.
Shortly before the position ”boot lid/tailgate closed” is reached, the speed of movement is reduced and the boot lid/tailgate moves slowly into the boot lid / tailgate lock. The boot-lid contact opens and the power module (PM) activates the drive for automatic Soft Close. At the bottom stop, the position switch in the drive for automatic Soft Close opens and the drive is switched off. The boot lid / tailgate lock is locked.
The speed at which the boot lid/tailgate moves is known to the boot lid/tailgate lift due to the continuous evaluation of the linear sensor. In the boot lid/tailgate lift, this speed is compared to a path-time curve stored in the boot lid/tailgate lift. If the speed reported by the linear sensor is lower than the nominal value stored in the time-path curve, the boot-lid mechanism is switched off (blockage identification).
A repeat lock facility prevents the hydraulic pump overheating. If the hydraulic pump has been in operation for longer than two minutes, operation is blocked for approx. six minutes. After this waiting period has elapsed, operation of the boot lid/tailgate lift is possible once again.
Malfunctions
A boot lid / tailgate movement is prevented
Emergency mode
In the event of system failure, the hydraulic valve is opened. The boot lid/tailgate can be opened and closed manually by exerting little pressure.
Switching off the drive for automatic Soft Close
If the power module (PM) does not detect that the drive for automatic Soft Close has reached the upper or lower limit stop, the SCA drive is switched off after 5 seconds. A fault is stored in the fault memory.
The functional sequence starts again when a signal change is signalled by the rear lid contact.
Antirepeat device of the drive for automatic Soft Close
An anti-repeat circuit prevents electronic components in the SCA control unit from overheating. The antirepeat device permits a maximum of 15 successive activations for the drive for automatic Soft Close before it switches off.
USA: The rear lid cannot be closed via the remote control.