After the rear wiper worked intermittently and finally quit working altogether, along with the rear hatch light was always on even when the hatch was closed, I decided to just replace the entire harness.
Its not the most difficult thing, but a few things that tripped me up;
need access to the right side of the hatch, when i pulled it out, it ripped the connection of the two plastic pieces by the right passenger seat belt assembly, it was tough to get back fitting correctly.
some of the connections are hard to remove, are there special tools? others were very easy.
the last connection on the loom is goes to the defrost, that one has a section you push in, and i had to simultaneously push in the section and pressure it toward the connector in order for it to be able to be reversed off the pin. the other thing is that the soldered connection on my car seems weak, and I was defiantly bending that back and forth a few times. It made me nervous that I was going to break it off!
Other than that, its just a lot of plastic removal, and removing the old harness out of the connectors is tough, I had to use a lot of force to break the white connectors out of the body of the car.
I chose to go with a new harness, but I think if you choose to fix all the wires in the loom it may be less time consuming. I just didn't trust the fix long term. I hope this harness is good for at least another 10 years!