"It is not so necessary any more that I know the answers, but now I desire
more to understand the questions."

Went out and pulled the wire harness loose from my trailer wheels. Blocked
it up. Took off the wheels and hubs. All looked good. Hooked up juice to
it, but nothing moved. Did find out how hot shorted 12v. wires get, and how
fast.

Aha, thinks I. Maybe the hub needs to be on there. So, I put the hub back
on, spun the wheel, hit the jumper, and it works like a charm. I guess the
activation of these brakes isn't really a many parts moving at a time thing.
Looks like they probably move 1/8" or so.

So, it looks like I need to just chase down the bad connection/ground.

Which brings us to the next question. It is said these need to be hooked up
parallel, not series. There are two greens coming out of the magnet. How
would I find the hot and the ground? Can I just run two lines, and jump
them at the first wheel, then run the wires to dead end at the second wheel?
The other wires to the bulbs are all in another housing, so it is only two
wires.

And do I bring it back and cut the ground near the tongue, and put on two
eye connectors, and screw them to the frame?

Looks like all is good, just have a break somewhere in the wiring, or it got
smashed somewhere. Looked formidable at first, but chasing it down one
component at a time, eliminating this, and that, and gaining another level
of understanding in the process is nice. Trailer lights have never been a
good thing for me. I thought brakes would be similar, but since there are
only two wires, not as much as lighting. There is more to the controller,
and the different things different controllers do. Now that I'm going to be
doing more heavy duty towing, it is nice to get an introduction to these
systems, wiring them from the start, and troubleshooting them after install.

Thanks for the help.

Steve