vstech, Where would my power supply wire come from? I know I could install my own wire and tap/splice a nearby hot wire, but then I might overload the spliced wire. I could run my own wire from the battery to the fuse but the whole point is to avoid running a wire from the battery. I don't suppose the factory ran any extra (i.e. unused) power wires in the harness?
I'm just worried about current carrying capacity (ampacity). The seats probably draw 5A per motor, and if someone hits the memory button and it moves 4 or 5 motors at once, it could draw 25A, which would be the limit of the 12 gauge wires - if the wire I spliced into has its own load currently drawing current, it would melt. I really don't want to have to tell all of my passengers to move one motor at a time. It would be embarrassing.
Where do all of the fusebox's power wires originate? I.e., where is the place where all the power wires in the fuse box originally connect to the fat battery + cable?
tangofox, I thought about that, or even the rear window heater, because what are the chances someone will be moving the seat at the same time as opening a window, but I've been trained to prepare for every contingency so I can't help but think my first passenger after the swap will get in, move 3 motors on the seat simultaneously, while opening the window.
If all else fails, maybe I'll make a neat harness of my own, carrying a few power wires from the battery to the fusebox, and friction tape it to make it look inconspicuous. There are two free fuse slots (5 and d), and if I ever need more, I can add an aux fuse panel somewhere under the cluster. Or maybe I'm getting ahead of myself?