Trailer Hitch: Description and Operation
Functional Description, Fully Automatic Trailer Tow Hitch With Local Interconnect Network
The F01 can be fitted with a fully automatic trailer tow hitch. The fully automatic trailer tow hitch is operated via a button in the luggage compartment. The system features a control unit with local interconnect network bus connection to the trailer module. The control unit for the fully automatic trailer tow hitch reports the fault to the trailer module. The faults are stored in the trailer module and, if necessary, a Check Control message generated, which is displayed on the instrument cluster.
Component description
- Button and LED for the fully automatic trailer tow hitch Pressing the button once causes the ball head to pivot in or out fully automatically to the corresponding end position. 2 colored light-emitting diodes are built into the button (green and red). The indicator light shows the system status.
- Tailgate contact The tailgate or the rear window must be open when the trailer tow hitch is operated.
- Microswitch for trailer detection The microswitch for trailer detection is built into the trailer socket. If the trailer connector is inserted in the trailer socket, the ball head cannot be pivoted in.
- Hall effect sensor in the electric motor for the fully automatic trailer tow hitch The hall effect sensor is built into the electric motor. By means of the hall effect sensor, the entire pivoting distance of the ball head is detected. The rotational movement of the spindle is transmitted by the hall effect sensor as a hall effect sensor signal to the control unit for the fully automatic trailer tow hitch. In parallel to the hall effect sensor signals, the control unit detects the required current for the swivel motion. If, during the fully automatic pivoting in or out procedure, the permitted power consumption of the direct current motor is exceeded or the hall effect sensor signals cease, the swivel motion of the ball head is stopped. The ball head is pivoted back a short way in the opposite direction (reversed).
- Control unit for the fully automatic trailer tow hitch The control unit activates the direct current motor of the electric motor. The control unit has no direct connection to the bus system and cannot be programmed.
- AHM: Trailer module The trailer module is connected to the control unit for the fully automatic trailer tow hitch by means of a Local Interconnect Network. In the event of a system fault, the trailer module generates a Check Control message. The trailer module continues to serve as trailer detection. The trailer module identifies a trailer as connected if at least 2 loads are detected at the lighting output terminals.
Switch-on conditions
The following switch-on conditions must be fulfilled for the fully automatic trailer tow hitch:
- No overvoltage or undervoltage in the vehicle voltage
- Terminal condition >= terminal 30 B
- Driving speed < 5 km/h and speed signal is valid
- Tailgate or rear window open
- Trailer connector not inserted in trailer socket
IMPORTANT:
The system, with ignition switched off, is deactivated after no later than 30 seconds (LED goes out): In order to reactivate the system either:
- close the tailgate or door and reopen,
- switch on ignition or
- press the "Open central locking system" button on the radio remote control.
System functions
- Automatic pivoting in and out By briefly touching the button (for less than 1 second), the ball head pivots fully automatically from one end position to the other. The fully automatic pivoting in and out can be stopped at any time by pressing the button briefly again. The fully automatic pivoting in and out procedure can 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 pivoted in):- Short press on button: The ball head begins to pivot outwards.- Next keystroke: Pivoting outwards of the ball head is halted immediately.- Next keystroke: The ball head begins to pivot inwards.- Next keystroke: Pivoting inwards of the ball head is halted immediately.- Next keystroke: The ball head begins to pivot outwards.
- Reversing the pivoting movement If the permissible power consumption of the direct current motor is exceeded during fully automatic pivoting out or in (e.g. as a result of an obstruction, stiff movement or low ambient temperatures), the control unit for the fully automatic trailer tow hitch triggers reversing. The ball head's swivel motion is halted. The ball head is pivoted back a short way in the opposite direction (reversed). Further operation is now only possible by means of continuous operation of the button (manual operation). In the areas of the two end positions, reversing is disabled and higher power consumption permitted. This allows the ball head to be pivoted out of each end position with more force (e.g. to release the ball head if stuck).
- Pivoting in or out by continuous operation of the button This mode is triggered by pressing and holding down the button for the fully automatic trailer tow hitch for longer than 1 second. The ball head only pivots for as long as the button is pressed. If the button is pressed again, the ball head is pivoted in the opposite of its previous direction of pivoting. The ball head's swivel motion stops when the button is released. 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 power consumption permissible in this mode is exceeded, the ball head's swivel motion stops. The ball head does not pivot in the opposite of its previous direction of pivoting (no reversing in this mode). It is only possible to initiate automatic pivoting in or out once an end position has been reached in this mode
- Initialization If the switch-on conditions are fulfilled, the button for the fully automatic trailer tow hitch must be pressed and held down to initialize. During initialization, the entire pivoting distance and the two end positions of the ball head are detected in the control unit of the fully automatic trailer tow hitch. For this, the ball head must be fully pivoted at least once from one end position to the other. Once initialization has been successfully completed, the ball head is locked in one of the 2 end positions. The LED in the button lights up green.
- LED signals LED off : Starting condition not fulfilled LED lights up green : Trailer tow hitch in end position and start conditions are fulfilled LED flashes green (2 Hz): Trailer tow hitch in end position and trailer detected LED flashes red (2 Hz): Trailer tow hitch in motion or intermediate position LED lights up red: Under- or overvoltage detected LED flashes red (4 Hz): Fault in the control unit or excess current shutdown, no initialization
- Readjustment of the trailer tow hitch To ensure that the trailer tow hitch remains in the end position when it is pivoted out, the direct current motor is briefly driven every 60 seconds towards the end stop. The control unit for the fully automatic trailer tow hitch activates readjustment in the following conditions: Terminal 15 on and pivoted ball head in end position.
- Emergency function The cyclical readjustment of the pivoted ball head can lead to the ball head becoming mechanically stuck. In this case, the emergency function can release the ball head from the end stop . During the initial phase for pivoting the ball head in or out, a defined swivel motion must be achieved. This pivoting movement corresponds to a defined number of Hall impulses by the DC motor. The hall signals are detected by the hall effect sensor on the direct current motor. If a certain number of hall signals is not reached, the control unit switches to emergency function. In the emergency function, the direct current motor is cyclically activated 5 times (per cycle, 300 ms are activated with subsequent break of 200 ms). If the minimum number of hall signals is not reached, the ball head can only be pivoted in or out by continuously operating the button for the electrically pivotable trailer tow hitch.
- Emergency operation If the voltage supply is interrupted during operation, various signal statuses can be lost. Once voltage supply has been re-established, the button must be pressed and held for 5 seconds. This will switch the powertrain on (emergency operation).
- Undervoltage and overvoltage The control unit for the fully automatic trailer tow hitch detects undervoltage and overvoltage. Undervoltage: Vehicle voltage less than 9 volts. Overvoltage: Vehicle voltage is greater than 16 volts. If over- or undervoltage is detected during the pivoting in or out procedure, the ball head will continue to pivot until it has reached the end position. The fault is then signalled by the LED in the button. If over- or undervoltage is detected during continuous operation of the button for the fully automatic trailer tow hitch, the ball head can still be pivoted to the end position. The ball head's swivel motion stops when the button is released. The DC motor can then no longer be energized while the overvoltage or undervoltage persists.
NOTE: Electric motor can be replaced separately
In the event of a fault, the electric motor of the fully automatic trailer tow hitch can be replaced separately.
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.