Hello together, today I was supposed to connect an already laid charging line for a trailer to a Mercedes Sprinter, which was already under the driver’s seat ready. I got a relay pressed in the hand. A Hella battery relay with the No. : 4RC 011 152-007 But can’t rub me together as I have to tie it up. Connections A and B is clear : If the Plus line is opened with the switched off engine. What is completely unclear to me is the 4 pin plug for the control. an experience with it and can explain it to me. Image of the schematic I enclose.