Opel COMBO Owner's Manual page 212

210 Driving and operating
3. Insert the coupling ball bar in the
opening and push firmly up to the
stop.
Secure the coupling ball bar
correctly by moving the lever to
the locked position, shown in the
picture.
4. Attach the trailer.
5. Fold the socket forward.
6. Connect the trailer plug to the
socket.
7. Attach the breakaway stopping
cable to the eye on the carrier.
9 Warning
Towing a trailer is permitted only
when a coupling ball bar is fitted
correctly. If the coupling ball bar
does not engage correctly, seek
the assistance of a workshop.
Dismounting coupling ball bar
1. Disconnect the trailer plug.
2. Unfasten the breakaway stopping
cable.
3. Remove the trailer.
4. Move the lever of the coupling ball
bar to the rear position. Remove
the coupling ball bar by pulling it.
5. Move the lever of the coupling ball
bar to the front position.