On Thu, 04 Feb 2016 10:26:46 -0500, Pat wrote:

Regarding "How is this even possible?", I can think of two things. One
is mechanical - plugging that 2 wire connector in causes a short near
the socket. Can you unplug the other end of that cable and see if you
get the result?

Already tried and eliminated, thanks.

The more likely cause is a voltage on that two wire
cable turns on a transistor or some other device hard wihich then shorts
the incoming line from the power supply due to a bad part somewhere else
on the board. Good luck.

That's what I was wondering. If my DVM on resistance range doesn't use
enough voltage to switch such a transistor or diode into conduction, then
that could account for it. I'll try it again with an old-style AVO.