Replying to myself incase anyone wonders about this in the future. The mystery connector is a part of the passenger side side light circuit. It is fused with a 10A fuse. Don't ask me how I know...

Holy necro thread! Does anyone actually know where the power for C594 is drawn from? is it a direct connection to the battery? I want to hoover ~15A peak out of it to power a VHF radio but I don't want to melt the wiring or blow something up. I...