Craig:  I had tested continuity through the switch.  That's
why I was looking further.

Bill:  I traced back from a tail light--to that black box.
I put on my glasses and found the connector, yellow with
one wire in, two wires out, black/blue.

No continuity there, so I went back under to the switch
and retested.  Then I reversed the wires on the switch tabs
and my backup lights work.  Either I didn't do a good enough
job cleaning up the contacts or there is a wire break that
I flexed enough to make work again.  Time will tell.

Richard