All nodes on a malfunctioned communications circuit of a communications network are enabled to identify the location of the fault causing the circuit malfunction. Upon detecting an incoming signal impairment on the circuit, each node on the circuit first assumes that the failure is on the segment of the circuit immediately upstream thereof, and accordingly sends an identifier of that fault location to its downstream nodes. Each node periodically repeats sending its identifier to its downstream nodes. A node that has sent its identifier at least a predetermined number of times without receiving a similar identifier from another node upstream thereof or without having detected a normal signal during all that time is determined to have sent out an identifier that correctly identifies the fault location on the communications circuit. If, on the other hand, a node receives a fault location identifier from a node upstream thereof before it has completed sending its identifier a predetermined number of times, then that node would stop sending its own identifier downstream. And upon receiving the same fault location identifier from an upstream node a predetermined number of times, that node further recognizes that the received identifier represents the correct location of the fault. The fault location identification process is terminated if the signal returns to the normal condition during the process.