A few questions:

#13 - are there any intermediate connections downstream of that connector or nothing until the other end of the 15ft harness.

You were going to try reconnecting the factory radio - did you get a chance to do this?

In the photo I've attached where does the other end of the cable (with what likes like only 4 wires) go that can be seen plugged into the factory radio? You shouldn't have anything plugged into that radio as it is no longer part of the system.

I have a suspicion that you have run the 15ft cable the wrong way around. One end should go into the radio (via a short adapter cable that has the connector visible in photo number 13) and the other end plugs into the car's wiring harness that has been unplugged form the radio unit located next the battery. In my install the red CAN bus decoder box ended up in the dash, not in the trunk.


That said my experience is based on an Xtrons radio but I think they're all v similar.

Attached Images