I\'ve reported a few wiring harness problems, but they have all been stuff that can be fixed just by swapping a few pins on various connectors.Well, tonight I found the problem that has stopped me in my tracks. I had put the wiring harness in the aircraft, and I was connecting the various power and ground wires when I took a closer look at one of the wires. The GNS-430 Com power line is supposed to get a 10 amp fuse, but the wire is only 20 AWG. It needs to be 18 AWG if it is going to get a 10 amp fuse. If I had simply followed the notes that came with the harness, and I ever had a short, I could have a smoking wire before the fuse blew. If I use a 7 amp fuse to match the wire I could be looking at nuisance fuse blowing in service.So if any other builders read this, please pay close attention to the details of any vendor supplied wiring harness. Don\'t simply assume that it must be OK just because it comes from a reputable vendor. I have lost complete confidence in these wiring harnesses. I\'ll be contacting the avionics vendor tomorrow to see how we can sort things out.