GFCI question

[whitegs]

Brand new 2018 Tommy Bahama Interstate. First long trip and frequently had to reset GFCI outlet and at other times the GFCI circuit breaker. Often this occurred with nothing connected and often after having been driving and just having been plugged into shore power.
Since getting home I have tested the outlets with a three light outlet tester. When I plug into all of the outlets, I get two bright yellow lights and a dim red light. When I plug into a good outlet in the house, I only get the two yellow lights. I've tried to use a VOM on the outlets but not sure how to interpret the results. When I test the two main outlet slots, I get the correct 122 volts. When I try the voltage between one of the main slots and the ground slot, I often can't get a measurement.
I'm wondering it there is a problem with the wiring or is it not unusual to have the dim glow in the red light of the tester along with two bright yellow lights in what is essentially an ungrounded vehicle.
Any other explanation for the frequent need for GFCI resets?

[Al and Missy]

There should be a label on your tester to tell you what the combinations of lights mean.

On the outlet, the large flat blade socket is neutral, the small flat blade is hot, and the round pin is safety ground. The neutral is supposed to be connected to ground at the main power panel (in your house or the campground, not in the trailer). The partially lit red led may be telling you that there is a problem with the ground wiring in your trailer.

Testing with a VOM, you should read 120 volts between hot and neutral and hot and ground and 0 volts between neutral and ground. Disconnected from shore power you should see an infinite (high) resistance between neutral and ground.

Al