Joying Android head unit - subs stopped working

[mikev]

Hi all,

My 2013 128i - S676 Hifi stereo with the amp in the left rear of the trunk and the underseat subwoofers

I swapped in the universal 8.9" Joying head unit and used the E90 harness and canbus adapter as referenced in multiple other threads here.

The only thing I'm still having problems with is the underseat subwoofers are no longer working.

I can't seem to find the factory harness diagram, but I'm wondering if there's another wire that needs to have power just for the subs to work. I guess I assumed that with the harness and others posting that it all worked correctly that it would be basically plug and play.

Anybody with some insight would be greatly appreciated.