212 gtr215

Purchased used 2012 gtr215 and my battery has the standard pos & neg cables plus 2 thinner wires coming from under the instrument panel, the red one is connected to the pos terminal but the black is not connected to anything. Should that red & black connect to the pos & neg?

Aftermarket maybe a power plug, not a proper install whatever it powers, probably why the ground is disconnected. I would leave it disconnected, find what it is powering and do a proper install.