Found an old trick for chasing bad grounds on 737s that still works today

I was working through a flickering display issue on a 737-800 last Tuesday and spent two hours checking wiring diagrams and swapping boxes. Finally an older tech named Dave walked over, grabbed a simple test light with a resistor in line, and started probing the ground studs in the wheel well. He found a corroded splice near station 540 that the multimeter had missed completely because it showed continuity under no load. I had been relying on my Fluke 87V for everything and forgot that sometimes you need a loaded test to find a bad ground. Now I keep a dedicated test light in my tool pouch for those sticky intermittent problems. Has anyone else run into situations where the fancy digital stuff lets you down and an old school method saves the day?

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williams.amy4d ago

Oh man, "showed continuity under no load" - that part really hit home. I mean, I've been burned by that exact same thing with my own Fluke, thinking a connection was fine when it was just barely hanging on by a thread. It's almost embarrassing how many times I've swapped out a perfectly good box only to find out later it was a ground that looked good on paper but couldn't handle any real current. Honestly, sometimes I wonder if the fancy meters just make us feel smarter than we actually are, while old Dave over there with his light bulb is laughing all the way to the troubleshooting finish line.