PSA: Found a wiring diagram error in the 737-800 IPC that could save you hours

I was troubleshooting a weird intermittent fault on a 737-800's VOR receiver last month, and after three days of chasing my tail I decided to double check the wiring diagram in the IPC. Turns out the IPC showed pin 22 on the connector going to the wrong terminal strip. I called up a buddy at another shop and he confirmed the same thing - the diagram has been wrong since revision 6. The actual routing was two pins over from what was printed. I found the correction buried in a Service Bulletin from 2019 that nobody at my station had bothered to cross reference. Now I always pull the latest SB before I trust any IPC wiring for older frames. Has anyone else run into a persistent diagram error that cost them billable hours?

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1 Comment

angelaellis1mo ago

Oh man, that's a rough one. A buddy of mine, he's an avionics tech over at a regional, spent a whole weekend chasing a pitch trim issue on a CRJ-700. He swears the wiring diagram in the manual showed the auto-trim servo going to the wrong relay in the overhead panel. He finally found a red-penned correction taped to the inside of the avionics bay door that some old-timer had left there probably five years ago. Saved his bacon, but he was already out the Saturday and Sunday labor.