Reached the point to put power to the avionics. Everything powered up correctly but I had an issue with the communication bus with the Garmin G3x. Doing the system checks, sometimes the individual LRUs would start to log on correctly but then they would not. Only thing that would show as online was the primary flight display. Pretty much for the last week I have been troubleshooting the system and narrowed it down to the CANBUS high channel was sometimes shorting to ground. Normally this wouldn't be too big a deal to find. Just split the bus in to two sections and see which one was grounding. Split that section into two and so forth till you narrow it down. But in my case, the short was there, then it wasn't, then it was. Literally took every connector apart and checked the wiring for the short. About the time I would think I had it, the short would show up again. Took the bus apart three times and I guess the old adage of "Third time is a charm" was right on. On the third disassembly, I found one hair wire that had slipped outside the pin as I slid it on. That one hair was moving around and mostly shorting against the connector frame. Clipped the hair and the Garmin system logged on all its LRUs Finished tying up all the wiring that I had taken apart in my trouble shooting, I installed the external alternator and the associated wiring to get the main electrical bus hooked up. I also installed the pitot system and AOA tubing that will run from the wing root to the panel.