[Dave at Pelican Parts]

It doesn't. It's an add-on by some previous owner or mechanic.

The stock ground strap goes from a bolt on the end of the transmission to a stud on the bottom of the rear trunk floor. There's another ground that goes from the right side of the engine bay to the battery ground terminal, but that's it.

Sometimes people add another ground point from the engine to the battery. I haven't seen one running to the other side of the car before... Perhaps the ground point under the relay board was rusty or had problems of some kind?

--DD