If the wires are chewed through, they can be repaired properly according to toyota specification which is to use an F crimp type joint and cover it with heatshrink tubing. And no soldering.
In my line of work we do this everyday dozens of times on broken/chafed/chewed wires.
However we also change out entire harnesses if they fall under warranty claim, that is sometimes an interesting job as we have to sometimes rip out entire interiors to bare metal.