You have the colour codes on your Diagram. Un tape the loom on the back, skin off wire a little, and voila!!I'm eager to get my old G back out there at night also. So, I'm going to rip this black box off of it's mount and dissect it. Hopefully, these white blocks that are inside show that they are easily removable and not hardwired. If not, I'll get to cutting with my Dremel. I'll let you know what I find.
Chances are that one of you lighting downstream is short!