i dont remember what years it applies to, i think 09+? Pin 8 in the car is for an ethernet connection, if the pin is left in the plug-in adapter then it triggers faults. By removing the pin you keep anything from being plugged into the ethernet connection and avoid any faults.
if you bought a cable with pin 8 still in it:
(im using the silver ebay cable i have as an example)- unscrew the 4 allen screws (2.5mm i believe) then open the casing. Pin 8 will be marked. Heat up the solder with a soldering iron and once the solder starts to flow pull the pin out the plug end with needlenose pliers (i used locking surgical hemostats since i was in my office, and an extra person is helpful so you can keep the soldering gun on it) you want to remove the whole pin while still touching the solder or else it will harden and freeze into place again. screw everything back together, pretty simple if youve ever used a soldering iron/gun.