Soft Close Automatic system

With the Automatic Soft Close system, the car door only needs to be pushed/pulled gently into engagement with the lock. The Automatic Soft Close system then fully closes the door.

There are the following drives:

  • Drive, soft-close function for doors, driver's door
  • Automatic Soft Close system drive unit, front passenger door
  • Automatic Soft Close system drive, driver's side, rear
  • Drive, soft-close function for doors, passenger's side rear
  • Drive, soft-close function for doors, tailgate

Brief component description

Drive unit for soft-close automatic function in door

The Automatic Soft Close system for the vehicle doors is a stand-alone function. The only connections to the vehicle electrical system are Terminal 30B and Terminal 31 (load earth). The drive units for the Automatic Soft Close function assume operational status as soon as power is available from Terminal 30B.

The electronic circuitry for controlling and monitoring functionality is in the Automatic Soft Close system's drive motor. The sensor systems for the Automatic Soft Close system are in the door lock. The sensor system are of the hall effect sensor type. The hall effect sensors (locking pawl switch and rotary striker switch) detect the position of the rotary striker and the locking pawl.

With the Automatic Soft Close system, the doors only need to be pushed gently into engagement with the door lock. The change in status is detected by the hall effect sensors in the door lock. The electronics in the driver's door Automatic Soft Close system drive motor start the door closing sequence with a delay of 200 milliseconds. That prevents the motor starting before the lock bolt is in the rotary striker. The drive motor moves the rotary striker by means of the Bowden cable until the relevant hall effect sensor signals a change in status. The drive motor is then stopped. The locking pawl is engaged and secured in the rotary striker.

When the door is opened using the inside or outside door handle, the system moves back to its original position.

Slamming the door shut would make closing with the Automatic Soft Close system unnecessary. However, since it is necessary to ensure the door is really closed, the drive motor is operated nevertheless for safety's sake. The drive unit's electronic circuitry detects door slamming based on the rapid status change at the locking pawl switch and the rotary striker switch.

Location data is stored in the drive motor's electronics. Thus the control system always knows what the motor position is and can operate it in order to move it to a defined position. When the motor is running, the stop conditions are checked every 23 milliseconds. If the electronic circuitry fails to detect arrival at defined positions within 5 seconds the drive motion is cancelled, i.e., the power supply to the DC motor is deactivated. After that, a change in status signalled by the hall effect sensors is sufficient to start it up again.

The driver's door Automatic Soft Close system drive motor has a repeat lock circuit to prevent the motor overheating. After activation and operation 15 times (15 increment counter), the drive motor is electrically locked out for approx. 2 minutes.

Index Explanation Index Explanation
1 Door lock 2 3-pin plug connection, connection between electronic component in drive motor and hall effect sensors in door lock
3 Bowden cable 4 2‐pin plug connection, connection for voltage supply
5 Drive unit for Automatic Soft Close in the door

Drive, soft-close function for doors, tailgate

The electronics for controlling and monitoring the soft close function are located in the tailgate Automatic Soft Close system drive. The sensor system for the Automatic Soft Close system is located in the tailgate lock. The sensor system consists of a group of microswitches (locking pawl switch and rotary striker switch). The position of the rotary striker is recorded with the locking pawl switch (open, preclosed, closed).

The drive is connected to terminal 30B. The fuse is located in the rear power distribution box.

When the locking pawl switch is actuated by the tailgate being lightly pressed into tailgate lock (the tailgate is then in the preclosed position), the tailgate Automatic Soft Close system drive is triggered. The drive electronics initiate the tailgate lock closing action. The drive moves the rotary striker via a Bowden cable far enough for the locking pawl switch and rotary striker switch to indicate a change in status. The lock pin is then engaged in the rotary striker and secured. Activation of the drive is stopped. In order not to obstruct the opening procedure, the drive reverses and again releases the Bowden cable.

It is still always possible to close the tailgate by hand.

The tailgate Automatic Soft Close system drive has a repeat lock which prevents the drive from overheating. After activation and 10 operations (counter up to 10 increments), the drive is electrically blocked for approx. 20 seconds. The drive can then be reactivated.

Index Explanation Index Explanation
1 Drive, soft-close function for doors, tailgate 2 Bowden cable, mechanical connection to the tailgate lock
3 Electrical connection to the tailgate lock 4 Webbed plate with planetary gear train underneath
5 Stop element 6 Direct current motor
7 Electronic component 8 six‐pin plug connection

System functions

Functional networking of the soft-close automatic

The following graphic shows the functional networking of the automatic soft-close (shown: left hand drive vehicle).
Index Explanation Index Explanation
1 Footwell module (FRM) 2 Junction box electronics (JBE)
3 Front passenger-door lock 4 Automatic Soft Close system drive unit, front passenger door
5 Front passenger side door lock, rear 6 Drive, soft-close function for doors, passenger's side rear
7 Power distribution box, rear 8 Tailgate lock
9 Drive, soft-close function for doors, tailgate 10 Drive, soft-close function for doors, driver's side rear
11 Rear driver's door lock 12 Automatic Soft Close system drive, driver's side, rear
13 Driver's door lock

Notes for Service department

Diagnosis instructions

An error detection for the drives of the automatic soft close is only possible to a limited extent. Since the automatic soft close drives are not connected directly to the control unit, there are no diagnostic jobs available to actuate and request the status of the drives.

It is not possible to differentiate between a faulty lock, a short circuit to earth or a mechanical jamming of the lock in the event of a detected fault state.

If a fault occurs, check the drive according to the wiring diagram.

 

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