What was it? Poor DIY stuff. The black wire (w/ red+white) is what you need to chase down; the white connected to the larger gauge red should just follow to a ground...it's possible they ran this red all the way to the battery (you might want to check). What the black is...who knows? Perhaps phone charger (but doesn't look right), radar detector, etc. My guess is that it runs somewhere behind the center stack...pull off the center side trim and have a look. I would guess that (based on connection) the black isn't zip-tied (but then again, who knows), you might just be able to pull it out.
What I would do... Disconnect. Remove. Smile.
