Towing Hitch Release

Functional Description For Fully Automatic Trailer Coupling With LIN

The F01 can be equipped with a fully automatic trailer coupling.

The fully automatic trailer coupling is operated using a button in the luggage compartment.The system has a control module with LIN bus connection to the trailer module. The control module for the fully automatic trailer coupling reports faults to the trailer module. The faults are stored in the trailer module and, if necessary, a Check Control message is generated and displayed in the instrument cluster.

Component description
- Button and LED for the fully automatic trailer coupling
Pressing the button triggers fully automatic pivoting in and out of the ball head up to the relevant end position.

There are two coloured LEDs integrated in the button (green and red). The indicator lamp shows the system status.

- Luggage compartment lid contact switch
The luggage compartment lid or rear window must be open during operation of the trailer coupling.

- Micro-switch for trailer detection
The micro-switch for trailer detection is installed in the trailer socket. If the trailer connector is inserted in the trailer socket, the ball head cannot be pivoted in.

- Hall sensor in the drive for the fully automatic trailer coupling
The Hall sensor is integrated in the drive. The Hall sensor detects the entire pivot path of the ball head.

The rotary motion of the shaft is sent by the Hall sensor as a Hall-sensor signal to the control module for the fully automatic trailer coupling.

In parallel to the Hall-sensor signals, the control module detects the required current for the pivoting movement.

If the permitted current consumption of the DC motor is exceeded during the fully automatic pivoting in and out or the Hall-sensor signals do not arrive, the pivoting movement of the ball head is stopped. The ball head is briefly pivoted back in the opposite direction (reverse).

- Control module for the fully automatic trailer coupling
The control module activates the DC motor of the drive. The control module has no direct connection to the bus system and is not programmable.

- AHM: Trailer module
The trailer module is connected via the LIN with the control module for the fully automatic trailer coupling. In the event of a system fault, the trailer module generates a Check Control message.

The trailer module also serves as trailer detection. The trailer module detects a trailer as connected when at least 2 loads are detected at the lighting outputs.

Switch-on conditions
The following conditions required for switch-on for the fully automatic trailer coupling must be met:
- No overvoltage or undervoltage in the on-board supply voltage
- Terminal condition >= terminal 30 B
- Driving speed < 5 km/h and speed signal is valid
- Luggage compartment lid or rear window open
- Trailer connector not inserted in trailer socket

System functions
- Automatic pivoting in and out
Briefly touching the button (less than 1 second) causes the ball head to pivot fully automatically from one end position to the other end position.

The fully automatic pivoting in and out can be stopped at any time by another brief press of the button.

The fully automatic pivoting in and out can then only be started when the ball head is in one of the two end positions or if the fully automatic pivoting in and out was stopped by pressing the button.

The control function of the button is as follows (initial position: ball head articulated inwards):
- Short press on button: The ball head starts to pivot out.
- Next press of button: The ball head pivoting out is stopped immediately.
- Next press of button: The ball head starts to pivot in.
- Next press of button: The ball head pivoting in is stopped immediately.
- Next press of button: The ball head starts to pivot out.

- Reversing the pivoting movement
If the permitted power consumption of the DC motor is exceeded during the fully automatic pivoting in or out (e.g. due to an obstruction or sluggish movement at low ambient temperature), the control module triggers reversing for the fully automatic trailer coupling. The pivoting movement of the ball head is stopped. The ball head is briefly pivoted back in the opposite direction (reversing).

Further operation is now only possible with sustained operation of the button (manual operation).

In the areas of the two end positions, reversing is suppressed and higher current consumption is permitted. This enables the ball head to be pivoted out of the end position with more force (e.g. to loosen a stuck ball head).

- Pivoting out or in by means of sustained operation of the button
This mode is initiated by an operation of the button for the fully automatic trailer coupling that lasts longer than 1 second.

The ball head only pivots as long as the button is pressed. When the button is pressed again, the ball head pivots in the opposite direction to before. If the button is released, the pivoting movement of the ball head stops. A further pivoting movement can only be performed in this mode. Increased current consumption by the DC motor is permissible in the continuous button-operated mode. If the current consumption permitted in this mode is exceeded, the pivoting movement of the ball head stops. The ball head does not pivot in the opposite pivot direction (no reversing in this mode).

Only when an end position has been reached in this mode is automatic pivoting in or out possible once again.

- Initialization
If the conditions required for switch-on have been met, the button for the fully automatic trailer coupling must be pressed for a sustained period for initialization.

During initialization, the entire pivot path as well as the two end positions of the ball head are registered in the control module of the fully automatic trailer coupling. To achieve this, the ball head must be completely pivoted at least once from one end position to the other end position.

After successful initialization, the ball head is locked in one of the 2 end positions. The LED in the button lights up green.

- LED indications
LED off: Start condition not met
LED lights up green: Trailer coupling in end position and start conditions met
LED flashes green (2 Hz): Trailer coupling in end position and trailer detects
LED flashes red (2 Hz): Trailer coupling in motion or intermediate position
LED lights up red: Undervoltage or overvoltage detected
LED flashes red (4 Hz): Fault in the control module or excess current cutout: no initialization

- Adjusting the trailer coupling
To ensure that the trailer coupling remains in the end position when articulated outwards, the DC motor is briefly activated towards the end stop every 60 seconds.

The control module for the fully automatic trailer coupling activates the adjustment under the following conditions: Terminal 15 On and ball head articulated outwards in end position.

- Emergency function
The cyclical adjustment of the pivoted-out ball head can lead to mechanical blocking of the ball head.

In this case, the emergency function can be used to release the ball head from the end stop.

During the start-up phase for pivoting the ball head out or in, a defined pivoting movement must be reached. This pivoting movement corresponds to a defined number of Hall impulses by the DC motor. The Hall impulses are detected by the Hall sensor on the DC motor.

If a certain number of Hall impulses is not reached, the control module switches to the emergency function.

In the emergency function, the DC motor is activated 5 times in cycles (in each cycle, activation for 300 ms with subsequent pause of 200 ms).

If the minimum number of Hall impulses is not reached here, the ball head can only be pivoted in or out with sustained operation of the button for the electric articulated trailer coupling.

- Emergency operation
If the power supply is interrupted during operation, various signal states can be lost. When the power supply returns, the button must be pressed for 5 seconds. This will switch the drive on (emergency operation).

- Undervoltage and overvoltage
The control module for the fully automatic trailer coupling detects undervoltage and overvoltage.
Undervoltage: Vehicle voltage less than 9 Volts
Overvoltage: Vehicle voltage greater than 16 Volts.
If overvoltage or undervoltage is detected while the ball head is pivoting in or out, the ball head pivots to the end position.

Subsequently, the fault is indicated by the LED in the button. If overvoltage or undervoltage is detected during sustained operation of the button for the fully automatic trailer coupling, the ball head can still be pivoted to the end position. If the button is released, the pivoting movement of the ball head stops. The DC motor can then no longer be energized while the overvoltage or undervoltage persists.

NOTE: Drive can be replaced separately

In the event of a fault, the fully automatic trailer coupling can be replaced separately.

No liability can be accepted for printing or other faults. Subject to changes of a technical nature