Just happened to stumble on a random red wire that seems to have been added after-market on our 2nd hand 2014 GC.
I can see the wire when I fold down the rear driver's side back seat, and also see it along the bottom of the B pillar next to the driver.
No issue with it - it's just a curiosity thing as it appears to be fitted after-market.
Car has a standard Hayman Reese towbar and trailer plug connector, and no other obvious 'extra' connections at the back of the car.
I don't feel like pulling off trims to trace the wire just yet, but wondering if this is a standard wire, or something different.
Cheers.