Servus, I have a Opel Vectra C Kombi Bj 2006 Now I have ordered from Westfalia a trailer coupling for retrofitting (removable) The coupling is of course fast mounted. Now I attach to the E-set. 1. the ground line is too short, but I will extend it. 2. How does it work with continuous current on pin 9 of the socket? Is this original switched on with these retrofit kits? Have some already mounted, but there is rarely Pin 9. Up to now it was also most with me it’s totally easy, screw on the can, plug in the small box and this in turn into the REC (control unit in the trunk). Meaning of this thing, I want to get my caravan. However, I also want to have light in there, etc. if I for example stay on the rest place for a short time. There is also the possibility to install a charging line in the car in order to charge an additional battery in the caravan, you can use the nic 3. The charging line causes me to break my head. This is plugged into the E-set of the trailer coupling, two cables lead to the car battery and one to the terminal 50 of the starter. In between, a relay is switched. But how does this circuit work exactly? Because the magnetic switch only gets so long voltage until the motor runs. Especially since I have the fear that the harness of the trailer coupling must burn away When starting. Here’s an example, the car battery is connected to the battery in the caravan via the charging line. The car battery is empty for xyz reasons. Does the starter not draw the current from the trailer? Because the cross-section of the charging line would be much too small for that. Hope you can help me with an “AHA” experience like so many times *g* Dear greetings Jan