There are three wires I cannot identify. 2 wires are together (one is white/black and the other is purple/black) in a single 2-wire white harness. The other is a solo black/blue wire that connects directly to a metal tab on back of radio. I believe the black/blue is the ground. Could the other two be for the steering wheel remote volume controls? Can't find any diagrams that include these three wires. Thanks.

 

I think those are for speakers.