Towbar wiring and random loose wire
 

Hi guys,

Looking for a bit of help.
Have a C200 Cdi (2004) estate which I've been roped in to fitting a towbar to.
To save me messing about with a multimeter, does anyone have a wiring diagram from the rear clusters so I can pick up from them. I have a relay kit.
Also, will the car need a visit to merc to reprogram anything? There are no reversing sensors fitted.

Also, just popped the rear covers off and found a random dangling wire. It's obvious where it joins, but just wanted to know what it was for before i go and solder it back together incase it has been removed for a reason!
Wire is pink with a blue tracer and seems to go up the rear n/s boot pillar.

Any help appreciated

Attachment 5056