I wanted to play with the WireViz Python package, which makes pretty wire diagrams. Installation was pretty easy, just created a virtualenv and installed with pip:
pip install wireviz
Documentation is pretty limited, but looking through the tutorials and the data models you get a pretty good idea of what’s possible.
I’m using the wiring diagrams from my guide to add an auxiliary audio input to a 2005 Subaru Outback, which is pretty simple, there’s an audio jack which connects to the Outback’s motherboard and the Outback’s FM audio module (and ground).
The input is a YAML document with three sections: * connectors - A list of connectors and the information about their port. * cables - A list of wires (and their information, e.g. gauge). * connections - A lists of ports that should be connected via each cable.
I had a pretty simple example, but it ended up being quite a bit of YAML:
connectors: RADIO: &radio # Since we only care about two of the pins, refer to them directly. pinnumbers: [31, 32] pinout: [FM R, FM L] type: Outback Radio Module show_name: false show_pincount: false hide_disconnected_pins: true MOTHERBOARD: <<: *radio type: Outback Radio Motherboard AUDIO: pincount: 5 pinout: [GND, L OUT, L IN, R IN, R OUT] type: 1/8" Stereo Audio Jack subtype: "RadioShack #274-246" show_name: false show_pincount: false GROUND: pinout: [GND] type: "Ground" show_name: false show_pincount: false cables: W1: &wire wirecount: 2 gauge: 22 AWG colors: [RD, GN] category: bundle show_name: false show_wirecount: false W2: <<: *wire GND: wirecount: 1 gauge: 22 AWG colors: [BK] show_name: false show_wirecount: false connections: - - RADIO: [31,32] - W1: [1-2] - AUDIO: [4,3] - - MOTHERBOARD: [31,32] - W2: [1-2] - AUDIO: [5,2] - - GROUND:  - GND:  - AUDIO: 
The only thing I couldn’t figure out was how to list two pins with the proper names and pins numbers, but ignore all the other ones. Note a huge deal for a 36-pin connector. See the comments below, this is doable, although a little awkward!
It did create a fairly pretty diagram after running wireviz subaru-wiring.yaml and is certainly easier than directly using graphviz. It creates a SVG, PNG, bill of materials, and HTML page (with the bill of materials and image on it). Overall, I’d use it again if I had a need!