Matt167, here's a very generic explanation of what should be happening. When the brake switch engages (circuit closes) the power goes into the turn signal switch and get directed to the front and rear lamps. When you pull down on the lever, the left side is run through the flasher and the right (rear) brake power continues on un-interupted. When you push up on the lever, the left(rear) power is un-interuppted and the right side is run through the flasher.

This is why I said to test at the signal device, you should have 1 power coming in (from the brake switch) and the turn signal device breaks it into 3 (three!) power wires going out. 2 of those will be flashing (dependant on lever position) and the other will be the opposing rear brake light.

I know this explanation is crude.. I don't write as good as Glennsexton but I'm trying... Hope this helps and take a moment to digest what I've written.. I'll think on it some more and see if I can't explain it better.