Mazda and Yazaki redesign the harness to suit the robot

The component that resists the robot

Body shops weld, paint shops spray and presses stamp, all with a consistency that no manual operation could match. But the wire harness has largely been left out of that story. It distributes power and transmits data throughout a vehicle, yet it is still a product assembled mostly by hand. To accommodate differing vehicle specifications, a large number of wires and terminals must be combined, and many of the manufacturing processes are still performed manually. A 2021 academic review put the manual share of harness production at up to 90 per cent.

Mazda Motor Corporation and Yazaki Corporation say they have made a dent in that figure. On 15 October 2026, the two firms announced that wire harnesses made with a new production method have been adopted for the first time in the all-new MAZDA CX-5. The work behind it began in early 2022, with the aim of advancing automation and bringing harness production closer to the vehicle assembly plant.

The announcement is more instructive than a typical automation milestone, because the robots are not the main character. The order in which the engineering decisions were made is.

Why equipment alone was never going to work

Harness production involves many delicate and complex manual processes. That is the root of the difficulty, and it explains why so many earlier attempts stalled. Installing equipment or deploying robots around an unchanged harness design runs into the same obstacle each time. Limp, branching bundles of wire do not behave like rigid parts, and a robot cell built to cope with every possible variation becomes slow, costly and fragile.

AMS has explored this challenge, including the stubborn problem of handling flexible wire and the argument that design-for-automation principles can matter more than simply buying more sophisticated machines. Mazda and Yazaki appear to have taken that logic to its conclusion.

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Redesigning product and process together

The two firms collaborated from the early stages of vehicle development and reviewed harness variants, specifications, structures and manufacturing processes with automation in mind. They redesigned the products and the production processes at the same time, which improved manufacturing capability and operational efficiency and made competitive manufacturing possible. Transcending the traditional boundaries between an automaker and a parts manufacturer, in their words, meant combining expertise and technologies from the outset.

The carmaker settles the design, passes a specification down the chain, and the supplier works out how to build it, usually with people. Here the harness was shaped to suit the machine and the machine was shaped to suit the harness.

Through optimisation of the entire vehicle, including these initiatives, the number of wire harness variants in the all-new MAZDA CX-5 fell by approximately 80 per cent compared with the previous-generation model. Variant count is the quiet driver of harness complexity.

Each variant brings its own parts, its own changeover and its own chance of a build error. Automated cells thrive on repetition, so removing four variants in five does not merely tidy the bill of materials. It turns a line that could only be run by hand into one that a robot can run profitably.

What the Mine City line does

Component parts procured by Yazaki are assembled into finished wire harnesses at a Yazaki affiliate’s plant in Mine City, Yamaguchi Prefecture, where the automated production line pictured above is installed. The firms are open about what this achieves for manufacturing capability. It improves efficiency across the operation and, as they describe it, lets domestic production respond flexibly to fluctuations in demand and changes in the external environment.

There is also a workforce dimension to consider. The firms also aim to support the sustainable development of regional manufacturing capabilities while fostering the next generation of talent and preserving manufacturing skills and expertise. Automation and skills preservation are often presented as rivals. Here they are presented as partners, with the engineering knowledge of the harness staying in the region rather than draining away.

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What the executives say

Kazuhiko Sumi, Corporate Leadership Executive Officer and CSCO at Mazda Motor Corporation, links the project to the carmaker’s wider manufacturing strategy.

“This initiative embodies the supply chain structural transformation and “Mazda Manufacturing Innovation 2.0” outlined in our 2030 Management Policy. Through proactive co-creation with our business partners, we have combined expertise and manufacturing capabilities to reduce component variants, bring production closer to vehicle assembly sites, and advance automation. These efforts have strengthened both our cost competitiveness and our ability to respond to change, helping us achieve more competitive manufacturing. We will not limit the application of these achievements to the all-new “MAZDA CX-5.” We will also leverage them to support the development of regional manufacturing capabilities and the transfer of technologies and skills to future generations. Together with our partners, we will continue creating new value for our customers.”

Kunio Tsuyuki, Senior Managing Director at Yazaki Corporation, is careful about describing automation's purpose.

“This initiative reaffirmed my belief that when companies share the common goal of delivering greater value to customers, automakers and suppliers can combine their expertise and technologies beyond traditional organizational boundaries to create new sources of competitiveness. In particular, our efforts to advance automation are not simply about reducing labor requirements or lowering costs. They are important initiatives that contribute to stable quality, higher productivity, skills transfer, and ultimately sustainable manufacturing. Through continued co-creation with Mazda, we will further advance manufacturing innovation and supply stability while delivering safe, reliable, and high-quality products to our customers.”

Tsuyuki’s list of benefits is worth noting. Stable quality and higher productivity come ahead of labour savings, which is the right order for a product as safety-relevant as a harness.

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The supply chain dividend

The supply chain gains are real, though they follow from the manufacturing decisions rather than driving them. Wire harnesses have long brought inventory management difficulties, along with production and logistics operations that grow more complex as the variety of parts increases. Manufacturers have also had to respond to changes in the business environment. Near-site production helps on several fronts, contributing to supply stability, greater efficiency in production and logistics, and reduced environmental impact. The catch has always been competitive cost, which is exactly what the automation and the variant reduction address.

The finished harnesses travel from Mine City to Mazda plants in Hiroshima and Yamaguchi prefectures, a short domestic route that improves efficiency and resilience across the entire supply chain.

A template for future models

Both firms plan to apply the knowledge gained to wire harnesses in future vehicle models, and to keep working towards a highly competitive supply chain and sustainable manufacturing through stable supply, improved production and logistics efficiency, and reduced environmental impact.

The harder test lies ahead. Electrical architectures are changing, and a harness designed around fewer variants and automated assembly will need to survive that shift. If it does, Mazda and Yazaki will have shown something useful to every vehicle manufacturer still treating the harness as a purchasing line rather than a design decision. The robots in Mine City matter, but the meeting between harness engineers and vehicle engineers at the start of the programme mattered more.