BroncoAl wrote:
It's plugged into a 20A GFI breaker on the front porch with an adapter to the 30A cord. How do I go about trouble shooting the problem if there is no obvious problem?
If it doesn't trip a GFCI & you are no longer getting a shock from the trailer I wouldn't worry about it. It could be a very high resistance fault, for example capacitive coupling, etc that doesn't produce enough current to cause a problem. If you still want to chase it down, measure the ground current while switching off each breaker.