Harness Failures: What’s to Blame? | 2017-04-13 | Assembly Apr 13, 2017When a wire harness fails, the testing system must be able to quickly pinpoint where and why it happened. Harness technicians at Boeing, Airbus and other aerospace manufacturers use the B-LRT tester to quickly find unreliable ground circuits in aircraft. Photo courtesy MK Test Author: Jim Camillo Common Reasons for Failure in Engine Control Modules - J Injector wiring harness The third thing that can cause failure in the ECM is the Injector wiring harness or the sensor wiring harness. Once again corrosion or breaks in the internal wiring in the harness can cause a short in the ECM or corrosion can enter the ECM through the wiring harness.