I have a harness with closed connectors (about 30 pins in each one of them),with about a dozen of twisted shielded wires. need to mark them to know which one is which. Tried to connect a needed pair to a ac power supply and find a wire with ac sensor, but on the low voltage shield blocks the signal, on a higher voltage sensor reacts on every wire. Please help, is there determine to were every wire belongs to? Thank you.