Any one here that knows 2020 & newer bmw m340i subwoofer wiring? Need help

[ssmokeyy]

So I told a friend I would help him out. He has a 2020 bmw m340i with harman system.. I built him two custom fiberglass subwoofer boxes paint matched to his car. Now we got a kicker keyloc to tap the subwoofer wiring for signals. So I looked up alldata and found the wiring needed in the back wall. Pass side factory sub is blue/gray and white/black. But the info alldata doesn't have is witch wire is positive. I have spent 4 hours looking online, got on dei database, pulled the front seats and removed the subwoofers but no markings anywhere.  Does any one here know what wires would be the subwoofer positive for each factory subwoofer?