Tow bar caravan/trailer wiring
13 pin Europlug   12N connector (black)  

Black 12 N pin plug
Looking at socket on rear of vehicle
Pin Pin

Function
1 Yellow   1 Yellow Left indicator
2 Blue   2 Blue Rear fog lamp
3 White   3 White Common for lighting circuits
4 Green   4 Green Right indicator
5 Brown   5 Brown Right tail light
6 Red   6 Red Brake lights
7 Black   7 Black Left tail light and number plate
  12S connector (grey)   7 pin plug & socket
8 Pink   1 Yellow   Reversing light
9 Orange   4 Green   Permanent 12V
10 Grey   6 Red   Switched 12V / Refrigerator
11 White/black   7 Black   Common for refrigerator
12 White/blue   5 Brown   Reverse sensor
13 White/red   3 White   Common for permanent 12V
      2 Blue   Battery charging supply