The red, black, and green all appear to trace back to my Rydeen Duo2 reverse camera. This is confusing since it's not how the
manual recommends connecting it. I did find a similar wiring setup for the
Duo3, which seemed to indicate that red should go to ACC and green to the reverse trigger.
This seemed simple enough assuming the orange harness wire (BACK in the chart above) is the reverse trigger. The camera instead activates when turning on the headlights though.
From what I can tell, the singular blue harness wire is not the amp trigger as it had been with my two previous harnesses. Instead, it's apparently the orange and black.
Unfortunately I had to stop troubleshooting due to a bad battery. I'll replace it tomorrow and try again.
UPDATE: Car wouldn't even jump without removing the harness (stereo was already disconnected) and disconnecting the battery for a minute. I'm assuming this is just due to my battery being borked, as I've known it was at low health for a while. Still, I can't help but wonder if the harness is causing a problem. I'm not too clear on what the CAN BUS attachment is for.