I'm installing a new head unit in the trunk. I will not be using the head unit in the dash. This means I need to get power back to that head unit in the trunk. Can I take the speaker wire that is connected to the dash head unit and splice that into the the power to the dash head unit? Then I can disconnect the speaker wire from the speakers in the trunk and power my new trunk-mounted head unit with the old speaker wire This way I do not have to pull up the carpet and run new wire. Is this safe or does it sound like a fire hazard?
I'm installing a new head unit in the trunk. I will not be using the head unit in the dash. The speaker wire is too small of gauge for power & ground wire. My motto is do it right by running new wires or don't do it at all.
It can be done, It depends how thick this speaker wire is. You might as well make the most out of this speaker wire, and use both leads/twist the wires together at each end, for connecting the positive supply from the front to the rear of the car. I assume your car has an earthed body, so of course use a bare metal connection for earth. If each wire has a ~1mm thick or greater core diameter, and you twist them together to use both, then it should be fine, I doubt they'd even get warm. PS: I have no idea why you'd not want to use the front head unit, and only use one in the trunk? It's probably at least as easy to run a new power wire from the battery to the rear, than it is to remove the head unit and muck around with the speaker wires!
