What does "pre-wired" mean in reference to the Tow Prep Package?
I just bought a 2013 Sienna L, and it has the Tow Prep Package for $220. I understand that the package includes mechanical components like a larger radiator, transmission cooler, etc, but I've also been told by my dealer that it is is "pre-wired". According to them, that means there is a wiring harness already installed in the rear underside, accessible by taking off the undercover, the large grey piece just in front of the rear bumper.
However, a local Trucking Thunder dealer says that "pre-wired" means nothing, and that they will probably thus have to run wires from the rear up the battery in the front, etc.
So my question is what does "pre-wired" really mean? Does it mean that there is an existing harness as described by the dealer that a separate towing harness can be plugged into? Or does the installer have to run wires up front, hook to the battery, etc.
I plan on hauling a Coleman pop-up camper with a 7 prong plug and electric brakes, as I did before with my Previa, but I'm not worried about the 7 plug. I just want to know if there really is something installed in the rear that will save the time and hassle of running new wires.
BTW, it appears that the tow prep package is the same for the 3rd generation Siennas, from 2011-2013.