This is the "I'm a moron" post..
I had one string of backbox GI out on my machine as well. I had blown it somehow using my multimeter (What was that spark? Where'd my lights go? DAMMIT!!!) right after I picked up SPace Shuttle. I still don't know what the hell I'm doing with a multimeter, but at least it's broken so I don't have to worry about frying anything else with it...
Anyways, fast foward like 7 months. I finally get around to poking in the backbox trying to figure out what the hell I did. Turns out that someone fused EVERY LINE OF GI IN THE BACKBOX.... why? I don't know. I can't find these four fuses in the schematic, but there they are, right next to the power board on my pin. Goes from the power board, down to the fuses, then over to a connector to the main harness. I guess it was pretty smart in retrospect, but aside from an idiot like me doing something stupid, not sure why you'd really NEED to fuse a GI line that only has 10 bulbs on it!
So I had shorted the GI line with my meter, and it blew the fuse. 35 cent fix. Replaced the fuse, all my GI now works. HELL YES. So, check it out and make sure someone didn't put in some pointless fuses that may be saving you some trouble.