Wire Like A Pro: Peeking Into Wire Harness Mastery

July 12, 2025 by Matt Varian 26 Comments

There are many ways to learn, but few to none of them compare to that of spending time standing over the shoulder of a master of the craft. This awesome page sent in by [JohnU] is a fantastic corner of the internet that lets us all peek over that shoulder to see someone who’s not only spent decades learning the art of of creating cabl e harnesses, but has taken the time to distill some of that vast experience for the rest of us to benefit from.

This page is focused on custom automotive and motorcycle modifications, but it’s absolutely jam-packed with things applicable in so many areas. It points out how often automotive wiring is somewhat taken for granted, but it shouldn’t be; there are hundreds of lines, all of which need to work for your car to run in hot and cold, wet and dry. The reliability of wiring is crucial not just for your car, but much larger things such as the 530 km (330 mi) of wiring inside an Airbus A380 which, while a large plane, is still well under 100 m in length.

This page doesn’t just talk about cable harnessing in the abstract; in fact, the overwhelming majority of it revolves around the practical and applicable. There is a deep dive into wiring selection, tubing and sealing selection, epoxy to stop corrosion, and more. It touches on many of the most common connectors used in vehicles, as well as connectors not commonly used in the automotive industry but that possess many of the same qualities. There are some real hidden gems in the midst of the 20,000+ word compendium, such as thermocouple wiring and some budget environmental sealing options.

There is far more to making a thing beyond selecting the right parts; how it’s assembled and the tools used are just as important. This page touches on tooling, technique, and planning for a wire harness build-up. While there are some highly specialized tools identified, there are also things such as re-purposed knitting needles. Once a harness is fully assembled it’s not complete, as there is also a need for testing that must take place which is also touched on here.

Thanks to [JohnU] for sending in this incredible learning resource. If this has captured your attention like it has ours, be sure to check out some of the other wire harness tips we’ve featured!

Splice CAD: Cable Harness Design Tool

July 7, 2025 by Matt Varian 29 Comments

Cable harness design is a critical yet often overlooked aspect of electronics design, just as essential as PCB design. While numerous software options exist for PCB design, cable harness design tools are far less common, making innovative solutions like Splice CAD particularly exciting. We’re excited to share this new tool submitted by Splice CAD.

Splice CAD is a browser-based tool for designing cable assemblies. It allows users to create custom connectors and cables while providing access to a growing library of predefined components. The intuitive node editor enables users to drag and connect connector pins to cable wires and other pinned connectors. Those familiar with wire harnesses know the complexity of capturing all necessary details, so having a tool that consolidates these properties is incredibly powerful.

Among the wire harness tools we’ve featured, Splice CAD stands out as the most feature-rich to date. Users can define custom connectors with minimal details, such as the number of pins, or include comprehensive information like photos and datasheets. Additionally, by entering a manufacturer’s part number, the tool automatically retrieves relevant data from various distributor websites. The cable definition tool is equally robust, enabling users to specify even the most obscure cables.

Once connectors, cables, and connections are defined, users can export their designs in multiple formats, including SVG or PDF for layouts, and CSV for a detailed bill of materials. Designs can also be shared via a read-only link on the Splice CAD website, allowing others to view the harness and its associated details. For those unsure if the tool meets their needs, Splice CAD offers full functionality without requiring an account, though signing in (which is free) is necessary to save or export designs. The tool also includes a version control system, ideal for tracking design changes over time. Explore our other cable harness articles for more tips and tricks on building intricate wire assemblies.

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A person holds a bundle of white, black, and blue wires. The left hand side of the wires are wrapped with black tape. The wires are inside a wire wrapping machine with a grey plastic "C" which rotates inside seven small pulleys. A large pulley in the background drives three of the pulleys to rotate the "C" around and wrap the wires with tape from the spool attached to the "C."

DIY Tool Makes Wrapping Wiring Harnesses A Breeze

February 26, 2023 by Navarre Bartz 17 Comments

If you’re making a lot of wiring harnesses, wrapping them can become a bit of a drag. [Well Done Tips] wanted to make this process easier and built a wiring harness wrapping machine.

The “C” shape of this wrapping machine means that you can wrap wires that are still attached at one or both ends, as you don’t have to pull the wires all the way through the machine. The plastic “C” rotates inside a series of pulleys with three of them driven by a belt attached to an electric motor. A foot pedal actuates the motor and speed is controlled by a rotary dial on the motor controller board.

Since this is battery powered, you could wrap wires virtually anywhere without needing to be near a wall outlet. This little machine seems like it would be really great if you need to wrap a ton of wire and shouldn’t be too complicated to build. Those are some of our favorite hacks.

If you’re wanting more wire harness fun, try this simple online wiring harness tool or see how the automotive industry handles harnesses.

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The Surprisingly Manual Process Of Building Automotive Wire Harnesses

July 27, 2022 by Dan Maloney 115 Comments

Even from the very earliest days of the automobile age, cars and trucks have been hybrids of mechanical and electrical design. For every piston sliding up and down in a cylinder, there’s a spark plug that needs to be fired at just the right time to make the engine work, and stepping on the brake pedal had better cause the brake lights to come on at the same time hydraulic pressure pinches the wheel rotors between the brake pads.

Without electrical connections, a useful motor vehicle is a practical impossibility. Even long before electricity started becoming the fuel of choice for vehicles, the wires that connect the computers, sensors, actuators, and indicators needed to run a vehicle’s systems were getting more and more complicated by the year. After the engine and the frame, a car’s wiring and electronics are its third most expensive component, and it’s estimated that by 2030, fully half of the average vehicle’s cost will be locked in its electrical system, up from 30% in 2010.

Making sure all those signals get where they’re going, and doing so in a safe and reliable way is the job of a vehicle’s wire harnesses, the bundles of wires that seemingly occupy every possible area of a modern car. The design and manufacturing of wire harnesses is a complex process that relies on specialized software, a degree of automation, and a surprising amount of people-power.

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