Test system and methods for testing a wiring harness. In one embodiment, a remote tester of the test system includes a connector member comprising a terminal end having one or more terminals configured to mate with terminals in an electrical connector of the wiring harness, and a tester control member integrated on a back end. The tester control member includes a housing that protrudes from the back end of the connector member, test circuitry electrically coupled to the terminals of the connector member, a wireless transceiver that communicates with a central controller to receive a test program, and a battery. The test circuitry performs a test on the wiring harness based on the test program, and reports test results to the central controller.