Today I called the vendor to talk to him. He was very cooperative and easy to deal with. He said that his employees are supposed to ?ohm out? each harness, but that something obviously went wrong with my harness. He offered to take the harness back, personally fix all the problems, and to give it a complete inspection - no charge.Power line - I originally was concerned that I could be looking at a possible smoke event if the 20 AWG power line ever shorted. However, Bob Nuckolls responded that although a 10a fuse was a bit much for a 20 AWG wire, and the wire would get hotter than desired if it ever shorted, it should not lead to a smoke event.I discussed this issue with the vendor. He explained that the Garmin specified 18 AWG wire requires an extra long pin to make room for a larger crimp area. In his opinion, this long pin has a real risk of later shorting out against other wires in the connector. He discussed the issue with his local FAA folks, and convinced them to allow him to use 20 AWG wire.Note - this power line ?Y?s? to go to two pins, so it should be possible to use 20 AWG wire from the pins to the Y, and 18 AWG wire the rest of the way. I didn?t think to bring this up with the vendor while I had him on the phone, but I requested he do this in the letter I sent with the harnesses.Many people on the e-mail lists I frequent wanted me to name the vendor, as they seemed to want to stay away from him. That was not the point of my messages. Even with the issues I had with my wiring harness I am still glad I chose the vendor I did. Any vendor can make a mistake. The important thing is how they deal with the mistake.My story was intended to advise that wiring harnesses should be completely checked out on the bench before installing them in the aircraft. Several of my problems would not have been noticed until I was doing the functional checks after installation, and it would have been very difficult to find and correct the problems with harness embedded in the aircraft. Don\'t just assume that any vendor supplied part is good without inspecting it.The wait for the wiring harness to return will mean I have to stop instrument panel work, and move on to other things. The good news is there is no shortage of other stuff to work on. I\'ll install the transponder antenna, run the coax to the cockpit, and then attack the wing leveler servo and ELT, etc.