[JRTJH]

The "easy way" is to use a lamp, turn it on and use it as a "test lamp" to check each socket....

A caution: If you have a removeable shore power cord, when you disconnect shore power, do it "at the trailer end of your shore power cord"... If you just unplug it from the outlet at your site or on the garage, the exposed pins may be hot and could electrocute someone who might inadvertently pick up the cord and touch the plug pins..... If you have a "permanently attached shore power cord that pushes into a cavity in the trailer" then those pins may be hot all the time and need to be protected/covered to prevent anyone from touching them.

The only way to remove power from those pins (on the recalled trailers), apparently is to either turn off the inverter or to remove battery power to the inverter by disconnecting the battery cables or inverter cables.