How to troubleshoot poor wiring harness connections in automotive manufacturing? Assembly experience

Poor wiring harness connections in automotive manufacturing might look like a connector that wasn't pushed in all the way, but troubleshooting it on the shop floor isn't that simple. I've seen connectors that made a 'click' sound but still showed unstable electrical readings; it turned out to be a terminal back-out because the locking tab wasn't fully engaged. When I look at these issues now, I…