Chasing intermittent problems
If it only fails sometimes, something is changing. Your job is to find what changes when it fails.
The short version
- Heat, vibration, moisture and load are the usual triggers. Figure out which one lines up with the failure.
- Wiggle test: with the circuit running and your meter on it, flex harnesses and plugs a section at a time.
- Leave a meter or a test light connected and keep watching while it fails. A reading during the failure beats ten readings while it works.
- Look hard at crimps, spade connectors and anything that moves with a slide or flexes over the axle.
Try it on a service call
Put the lesson to work on a hands-on troubleshooting case.