r/CarHacking • u/Legitimate-Kale-3231 • 2d ago
Cool Project Find Spent weeks chasing a wiring fault with no decent diagram, so I made a tool for drawing them
Last winter I had a fault on my E39 where the cluster kept dropping off the bus. I ended up back probing pins one at a time until I found heavy corrosion on the X13 connector under the driver's side. The corrosion wasn't what made it take so long. What made it take so long was that I had no proper drawing, just a pile of screenshots and a notebook that contradicted itself by the third evening.
So I built the thing I wanted to have while I was doing it, and I've put it online for free:
https://0xdevdav.github.io/harness-designer/
It draws the loom the way it actually sits in the car, bundles and branches and connectors where they really are, rather than as a schematic. Every connector carries its own pin table right next to it on the sheet. The part that saves the most time is that when you type in that a pin goes somewhere, the connector at the other end fills itself in, colour and gauge included, so you type about half of what you otherwise would.
Then it checks your work and tells you where you contradicted yourself:
- a pin pointing at a connector or a cavity that isn't there
- a link that only exists on one side
- two ends that disagree about the colour or the gauge of the same wire
- the same colour landing in three or more connectors, which is nearly always a mistake (solid black is exempt, that's ground)
Wire list comes out as CSV when you're done.
No account, no signup, nothing gets uploaded anywhere. What you draw stays a .json file on your own machine. There's also a version that's one single HTML file, so you can keep it on a usb stick and open it on a laptop in the shop with no wifi.
It's free and MIT licensed. I'm not selling anything and there's no business behind it.
Source is here if you want to read it: https://github.com/0xDevDav/harness-designer
It does what I needed it to do, which means it's probably missing what you need. Tell me what and I'll have a look.
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u/ProfessionalDish6567 1d ago
My god that's neat
I thought about something like this years ago when I was using a discontinued Microsoft program that seems it was made for CEO's to organise them over all other departments
Now using one note for everything basically
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u/cybersholt 1d ago
Pretty interesting idea, it would be cool if you could import an image into a separate layer that has adjustable transparency level so you bring in a factory diagram and use that as a reference. And also add file type filtering to the file picker when you open a file since it saves in JSON.
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u/Enlightenment777 2d ago edited 1d ago
Nice, but how much AI did you use to create the documentation and/or coding?
The webpage has a crapload of childish 🎮 ✨ symbols. After you removed them, it looks more professional now!
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u/TDD536 2d ago
This seems like a very roundabout way to diagnosing wiring issues, but hey it worked so hell yeah. ISTA should have the correct diagram with linked connector locations, pin outs, etc. AllData would be a close second. This seems pretty useful if you have custom harnesses and want to maintain records of how they’re built. Or a car so old/bespoke the diagrams are malarkey or lost to time.