Abstract: An apparatus and method for testing the integrity of wiring cables provides a transmitter and a receiver that electrically connect to opposite ends of group of wires to be tested. The transmitter produces a voltage test signal applied to a test set of wires and a different voltage reference signal is applied to a reference set of wires. At the receiver, indicator circuits interconnect the wires to a common bus. The reference signal is applied to the common bus and, when the test signal is present, the indicators operate to produce a display. The test signal can be cycled through a plurality of test sets making up the entire test group.