Wiring kit specifics:

•  Part number:305216300113
•  Number of pins:13-pin wiring kit
•  Wiring kit:vehicle-specific
•  Blinker monitoring:CAN
•  Coding / activation:required
•  Parking aid shut-off:yes
•  Dauerplus (terminal 30):included
•   Charging cable:optional
•  Power connection:rear

Towbar, to work correctly, requires a module. This is responsible for CAN communication with other modules:

• Engine - when towing it works differently to cope with extra load - sometimes switches additional fan to cool
• ABS / ESP module - these work differently when trailer is hooked to avoid jack knifing. 
• CECM - This power module distributes power in another way when trailer is hooked - also visually aids the driver when trailer is hooked on dashboard 
• OPS - This is coded so when trailer is hooked up sensors do not beep
• CAN gateway - trailer module is coded into the gateway (main comms hub) so the car and other modules know what to do
• RVC - reversing camera - similar thing to parking sensors - recognises the trailer on the screen switches off dynamic lines
• 5F Information Electronics - ensures entertainment system displays all the trailer info correctly.
• LED Trailer Module 69 - to assure correct operation of lights and communicate DTCs with Instrument Cluster 
• Westfalia-Automotive invented technology

Features:

• Vehicle specific CAN-Bus wiring
• Easy assembly
• Extremely reliable
• Complete functionality through connection to on-board electrical system
• Made in Germany