That helps a lot! Thanks for the idea. I took a Hobbs tractor headlight & attached it to the elec brake connector on the bumper. Without a load (no light, only VOM), the unit would only put out about 4V & the red light on the controller would never turn green, which happens when successfully connected to a complete elec brake circuit. But, when I attach the 12V 50W light, the same test will get you a full 12V...and a bright test light!

Thanks for the idea. We use 7 pin round connectors (like semis) on our pickups & trailers, so I took an old connector & attached the light.