I am chasing a strange problem w/ some 12 v electrical wiring (properly sized to carry a 5 v signal voltage. I've noticed that when a properly sized (OEM) to carry a 5 v signal voltage gets hot, often the signal voltage drops randomly to 2.3v or so. Assuming the electric connections are sound, clean and good , do 12v copper wires deteriorate due to old age, or heat exposure? continuity checks when 'cold' show no problem.