Alright, my neighbor showed up with his fluke multimeter. He's a professional electronic tech. To say my Harbor Freight multimeter is a POS is an understatement. Here are the readings with the reverse polarity fuses pulled and plugged into shore power.
The converter output is 14.3 volts.
The DC from the battery is 12.8 volts.
I'm relieved with these readings. Still need to figure out why no led light. I'm leaning toward the harness wiring being reversed.
Going to report back my findings ti Progressive Dynamics, I'll let you know where this heads. Thanks for all the input. As for me having a Harbor Freight multimeter, I loaned out my good one. The person I loaned it to denies borrowing it. While I don't need a $900 Fluke multimeter, I'll be spending a little more on a decent tool.
Take care.