I just took a look myself and I think I agree that there's no way the rear speakers can be working. I think I (we?) may have received a bad wiring harness?
Here's what I've found:
1) The CC3 diagram shows the following pinouts for the G socket:
View attachment 3207468
Note that G9-G16 are the front and rear speakers. The top 4 pins on the left side are front outputs and the top 4 pins on the right side are the rear outputs.
Here's that same socket on the actual wiring harness:
You can see the top right 4 pins aren't even connected. Obviously the CC3 isn't outputting any rear speaker signal via the G socket (but maybe it does via the RCA outputs? I didn't check)
2) I also thought they might be tying the front spekaer outputs together in the harness and outputting that signal to the front AND rear speakers. But they are not. If we follow the front speaker wires from the output on the G socket to their destination, you can see them here. It's the four that are looped a bit:
And if we look at the LX470 wiring diagram, we see this (the four wires are pins 9, 8, 19, and 18):
So they way they mapped this is:
CC3 -> LX470:
Front Left positive -> Front Left positive (FL works)
Front Left negative -> Rear Left positive (RL does not work)
Front Right positive -> Front Right positive (FR works)
Front Right negative -> Rear Right negative (RR does not work)
---
I can only think of a few things that happened:
1) I have a bad wiring harness (can anyone else check theirs to see if it has the rear speaker outputs hooked up on the G socket?)
2) Nobody's rear speakers work (false, as evidenced by other people saying theirs work)
3) The 2007 LX470 pins are different than other LX years that are working? I doubt this because Asanka is having the same problem on his 04 LC.
I'm going to ping Teyes support and see what they say, but would be awesome if someone with working speakers could look at their harness. I KNOW how much of a pain it is to pull it apart though.