The G63 can tow an impressive 7k lbs, but it does not come with a trailer brake controller. So I looked into my options for an elegant solution and I found that G-Wagon Accessories makes a custom wire harness that allows you to install a trailer brake controller into the car’s OEM system. The G-Wagon Accessories wire harness will plug into the OEM wire harness located in the rear cargo area on the driver side in the rear wheel well electrical compartment. It then runs up to the front of the driver area where you will mount the trailer brake control unit. The hardest part is to run the wire from the cargo area to the driver seat as the G wagon has tightly fitted carpets and interior trim panels. I ended up using a fishing tape to route the wire under the cargo carpet, under the rear seat, under the driver seat, up through the center console trim, up under the driver dash trim. I used a Curt Spectrum Trailer Brake Controller because it has a controller box I can mount under the dash with only a control knob visible. This allowed me to have a very hidden installation. The control knob can be screwed down or you can use mounting tape which is what I did so there was no damage to the truck…..however the mounting tape only stuck to plastic pieces so I ended up mounting it upside down on the side of the center console. There is not problem with this as it is a rotary knob and it makes the installation virtually invisible.
One annoyance….not with the trailer brake controller but with using the G for towing. The 7 pin electrical connector by the hitch in the rear faces down. This means your trailer cable is facing down thus making it a slight risk of getting hung up on something when you tow. I wish the G had a traditional rear facing 7 pin like virtually every other car on the planet. Just another oddity of the G. My solve is to eventually unhook the OEM plug and rewire to a new location.