A tone generator is used in conjuction with an inductive amplifier probe. You connect the tone generator to the wire you want to trace (and sometimes another wire to an electrical ground) and run the probe along the wire path following the tone you hear. If the tone drops off, you have a break / open circuit. Where the tone can be heard branching out along other wires or metal parts, you have a short circuit. A tone generator & probe are more effective at locating breaks / open circuits than short circuits. To locate short circuits, either a more expensive TDR (Time Domain Reflectometer) or a high-resolution ohmeter (or whetstone bridge) can be used to determine how far down a wire a short occurs. TDRs work by firing a pulse down a wire and by sampling the echo which gets bounced by open circuits, and either “sinked” or other anomolies by short circuits. The TDR measures the time between the pulse and anomolies in the echo to determine how far down a wire anomolies are. You need a “nom