The 2 AM pin-out surprise that made me triple-check every wire

I was doing a harness rework on a Cessna 172 at a small hangar in Wichita around 2 in the morning, chasing a nav light fault. The schematic said pin 22 should go to the strobe power, but the actual wire had been swapped with pin 14 by some previous tech, and no one left a note about it. I found it because the light flickered only when I wiggled the connector, so I started tracing each pin with my multimeter one by one. After three tries and a lot of cussing at the aircraft log, I realized the whole harness was built off a superseded drawing that matched the wrong serial number. I re-pinned the connector, tested everything twice, and wrote a big warning in permanent marker on the inside of the access panel. Now I always pull the actual airplane's wiring diagram, not the one from memory, especially on older birds. Has anyone else run into a mismatch like that where the paperwork lied to you in a real inconvenient spot?

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paulw5311d ago

Hell, I used to trust the drawings over my own eyes every time, figured the paperwork had to be right and my meter was lying. That one incident flipped me hard, now I verify every pin against the actual bird before I even pick up a crimper.

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