My instructor's 'always start with the wiring diagram' advice just saved a three-hour job

I was working on a Garmin G1000 install in a Cessna 172 last week, trying to find a power issue that kept popping a 5-amp breaker. My first thought was to start swapping parts, but I remembered my old tech school instructor, Mr. Jenkins, drilling into us to 'always start with the wiring diagram, even if you think you know the system.' I pulled out the manual and spent about 20 minutes tracing the circuit. Turns out, a previous installer had run a wire for a new GPS antenna through the same conduit as the main bus feed, and the insulation had rubbed through, causing an intermittent short. If I had just started replacing the avionics unit or the breaker, I'd still be there. That diagram showed me the exact wire run to inspect. Has anyone else had a simple piece of advice from training that stopped a huge headache later on?

2 comments

2 Comments

bethjackson23d ago

Heard a buddy waste a whole day ignoring @robin_schmidt57's fuel pump advice.

robin_schmidt5723d ago

That "start with the wiring diagram" rule is golden. My version was an old mechanic telling me to always listen for the fuel pump to prime before even touching a wrench.