“If the light came on, it meant current was flowing and the wire was good.” By the 1950s, harness manufacturers began using telephone stepper switches (relays) to continuity test each harness wire and verify its location in a connector.
Testing was fairly slow, and remained so for many years as automobiles required larger harnesses to power windows, seats and other standard features.
When electronic switches began being used in testers in the late 1980s, the speed of continuity testing increased significantly.
Automotive-harness manufacturers use testers to quickly perform continuity, hipot and componentspecific tests on complex automotive harnesses.
Here, operators plug in a harness for testing on the build board. When watching an operator test an automotive wire harness, one is reminded of old-time photos and TV skits about telephone switchboard operators of the 1950s and 1960s.