I've got a circuit with (2) 3 way switches (good) that operated a light just fine. I wanted to add a Leviton motion sensor at one end (it's capable of 3 way operation with a jumper). 1st problem is that the Leviton diagram doesn't fit the situation. The load was wired (not by me) as power through (like this http://www.homeimprovementweb.com/information/how-to/three-way-switch-option3.htm). So, there's the first question.

I started going through the motions to ID the travelers so I'd know what I was dealing with and things started getting interesting. I took all wires off both switches and energized one of the travelers and lo and behold I get 120V on one wire at the other end (good) and 46V on the other one (bad). So, I dig deeper. I take the load out of the picture and disconnect all wires, energize one trav and at the other end I get similar results results only 56V instead of 46V. I checked for continuity between all cond's and get zero Ohms. I'm stumped

So with one traveler energized, that wire shows 120 volts at the other end, and without changing anything, the other wire shows 46 volts?

If that is the case, you are only measuring an induce voltage on the other traveler.

Yep. That would make sense, because the voltage was higher (~57V) at the fixture (when I took everything apart) than at the far switch where I got 46V. I'm going to energize the other traveler this AM and see if I get the same results. The fact that I can't get continuity between conductors puts my mind at rest for fear of degraded insulation.

Now the issue is how to wire this PR180 with power through the switch with the load in line with (like the link I gave in first post). Leviton's diagram doesn't seem to fit this scenario unless I'M OVER THINKING IT.

OK seems you got it. I don't think you have any problem with the wiring.

The sensor on the other hand...

Do a search in the electrical forum for other posts on that sensor, there has been other people with the same problem. You can try contacting Leviton tech support, bit I remember other people did not get much satisfaction.

I, personally, have no experience trying to connect this sensor.

I always use Sensor Switch, much better product, works every time, and MADE IN THE USA. I refuse to buy Chinese crap when I can buy the same product made here.