Automatic Trunk Lid Actuation

Automatic Trunk Lid Actuation

Automatic luggage compartment lid actuation
The electrical automatic luggage compartment lid actuation will be offered in the E70 as of 10/07 and will be deployed for the first time as a spindle-driven system.
The upper tailgate can be opened and closed automatically by pressing a button. The lower tailgate lid is still opened manually.
The opening angle of the tailgate can be set in five stages in the Central Information Display menu using the controller. Here, the tailgate only moves up to a set angle.

Brief component description
The following components are described for the automatic luggage compartment lid actuation:

Spindle drives
The spindle drives are fitted in place of the gas pressure springs on the left and right of the tailgate. The spindle drive consists of the following components:







System wiring diagram - E70







System wiring diagram E71







Control units

Automatic luggage compartment lid actuation (HKL)







The automatic luggage compartment lid actuation (HKL) is fitted in the luggage compartment on the right on the equipment holder. The HKL controls and monitors the function of the automatic luggage compartment lid actuation.
The control logic is connected to terminal 30g. For the load current of the spindle drives, the HKL is also connected to terminal 30.
The automatic luggage compartment lid actuation functions between 9 V and 16 V. Outside of this range, the functions cannot be maintained.

Car Access System (CAS)
The Car Access System (CAS) receives the signal from the remote control or the ID transmitter and checks it. If the check (authentication) was successful, the CAS enables unlocking for the tailgate.

Junction box electronics (JBE)
The junction box electronics unlock the tailgate. The junction box electronics are plugged into the front power distribution box.

Operating elements

Tailgate pushbutton, outside tailgate
The tailgate pushbutton switches to earth. The signal of the tailgate pushbutton is picked up by the junction box electronics. The junction box electronics signal the status of the tailgate pushbutton via the K-CAN to the HKL.

Tailgate pushbutton, inside tailgate

E70
On the E70, the inside tailgate pushbutton is connected parallel to the outside tailgate pushbutton on the junction box electronics. This is why the junction box electronics make no distinction between the two tailgate push buttons.

E71
On the E71, the interior tailgate pushbutton is connected by a direct line to the automatic luggage compartment lid actuation control unit.

Tailgate pushbutton remote control
The radio signal of the remote control is received via the rear window aerial. The remote control receiver forwards the signal via the K-CAN to the Car Access System. The Car Access System has the central responsibility for the function of the central-locking system. The ID transmitter used in vehicles with Comfort Access has the same functionality as the remote control.

Tailgate pushbutton in the centre console control panel
The tailgate pushbutton is resistance-coded. The status of the tailgate pushbutton is of the by the control unit of the air conditioning system. The control unit of the air conditioning system sends the status across the K-CAN.

Contacts

Rear lid contact switch
When the tailgate is closed, tailgate contact switch switches to earth. The status of the tailgate contact switch is evaluated and made available by the junction box electronics.

Microswitch, lower tailgate







The contact of the lower tailgate is designed as a microswitch and it switches to earth. The status of the microswitch is evaluated by the HKL. If the lower tailgate is not correctly closed, the automatic luggage compartment lid actuation cannot be executed. The automatic luggage compartment lid actuation control unit generates a Check Control message.

System functions
The following system functions are described for the automatic luggage compartment lid actuation:
- Automatic closing and opening
- Position detection
- Blocking detection
- Repeat interlock
- Blocking conditions for movement of the tailgate

Automatic closing and opening
Activating one of the tailgate push buttons automatically opens or closes the tailgate. This does not include the tailgate pushbutton in the centre console control panel. This can only be used for automatic opening.
After release by the CAS, the junction box electronics unlock the tailgate. First of all, the drive of the Automatic Soft Close system is activated to relax the tailgate. Then the tailgate lock is activated.
The tailgate contact switch switches from closed to opened and the spindle drives are activated for opening.
The tailgate is opened fully or up to the set opening angle. If one of the blocking conditions (see 'Blocking conditions') is met during the luggage compartment movement, this stops the luggage compartment movement.
Briefly pressing the tailgate button during opening stops the opening.
The function "soft start" or "soft stop" is integrated in the HKL. This means that, shortly before it reaches the end stops, the tailgate is moved gently into the end stops in that the closing or opening speed is lowered. (Exception: no soft stop on closing). This is achieved by changing the pulse width of the activation voltage.
In vehicles with Comfort Access, the tailgate can also be opened when the vehicle is locked. Pressing the outside tailgate pushbutton opens the tailgate automatically. All this requires is that an ID transmitter that matches the vehicle is in the immediate vicinity of the vehicle rear end.
Automatic luggage compartment lid actuation cannot be activated while the vehicle is being driven, only when the vehicle is at a standstill.
As soon as it is partially opened, the tailgate can be moved by hand towards "OPEN" or "CLOSED".

Position detection
A motor is integrated in each of the spindle drives. Two hall effect sensors are fitted in the motor, deviation in against one another. This enables the direction of rotation of the motor to be detected. Furthermore, the distance and thus the opening angle of the tailgate can be detected on the basis of the hall effect sensor impulses. The hall effect sensor impulses are used, for example, to adjust the opening angle via the Central Information Display.

Blocking detection
The blockage identification takes effect on opening and closing the tailgate. A blocking of the luggage compartment movement on opening has the effect that the luggage compartment movement is stopped immediately. If the luggage compartment movement blocks on closing, the HKL activates the spindle drives briefly in the opposite direction (= reversing). If the tailgate remains blocked, the spindle drives are no longer activated.
Blocking is detected when the hall effect sensor impulses are not received or when the motor current rises.

Repeat interlock
To prevent the motors from overheating, a repeat interlock is integrated in the HKL. The motor running time is added up for the repeat interlock. If the total exceeds an entire running time of 2 minutes, new operation is not accepted. An action that is already running is always completed. After a cool-down phase of 6 minutes, a motor run time of 2 minutes is possible once again.

Blocking conditions for movement of the tailgate
To prevent vehicle damage, the tailgate must not be operated in various situations.

The blocking conditions are listed below:

Blocking conditions Explanation / note
Driving speed vmax greater than 3 km/h Exception: a close command is completed. Speed signal from the instrument panel via K-CAN.

Ambient temperature less than -30 °C Signal of the ambient temperature from
and +80 °C the instrument panel via K-CAN

Vehicle voltage 9 V to 16 V

Lower tailgate not closed Cancellation of an ongoing tailgate movement, blocking operation of the tailgate. Opening remains possible.

Engine start (status "terminal Signal from CAS via K-CAN. Cancellation
50 on") of an ongoing tailgate movement, blocking operation of the tailgate.

In the event of an invalid speed or temperature signal, the tailgate can be moved.

Notes for Service department

Replacing the spindle drives
A faulty spindle drive is to be replaced completely.
On replacement of the spindle drives, terminal 30g should be switched off. Otherwise, a fault entry is generated and the automatic luggage compartment lid actuation will not work.
After replacement of one or both spindle drives, the automatic luggage compartment lid actuation must be initialized. Use the service function Initialize automatic luggage compartment lid actuation".

Replacing the automatic luggage compartment lid actuation control unit
After replacement of the automatic luggage compartment lid actuation control unit or spindle drives, it is necessary to relearn the upper end stop. To do so, the tailgate is moved at the upper end stop to block.
Blocking the tailgate and thus suppressing the hall effect sensor impulses of the spindle drives marks the point of the maximum opening angle of the tailgate. A value of approx. 5 % of the total hall effect sensor impulses is subtracted from this point. This is the future opening angle of the tailgate. The point is also referred to as 'Soft-stop'.
Soft-stop prevents the tailgate from opening up to the end stop, which could damage it.
The lower end stop is determined by the change of the tailgate contact switch of the tailgate lock from opened to closed.

National-market versions

US version
The luggage compartment movement only starts after the tailgate button has been released.
It is not possible to close the tailgate using the remote control.
No liability can be accepted for printing or other faults. Subject to changes of a technical nature