Allen Richards' Blog: It Takes a Lot of Wiring to Keep a Modern Vehicle Moving (Witness this Bentley’s Harness)

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From the June 2016 issue

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Almost as much as fuel, electronic signals are the lifeblood of a modern vehicle. And the Bentley Bentayga is a poster child for just how complex today’s electrical systems can be. If it doesn’t have the most-elaborate wiring in the civilian ground-bound vehicular world, it’s close. The Bentayga offers four long-range radar systems, up to 12 short-range ultrasonic parking sensors, six camera systems, dozens of lighting elements, a 48-volt roll-control suspension system, a champagne fridge, an 18-speaker stereo, a watch winder, and seats that can warm, cool, and massage occupants. And all of it is designed to withstand heat, cold, dust, moisture, and electromagnetic interference. Presented on this page is what might look like an aggressive case of rosacea but is actually the Bentley’s complete wiring harness.

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>100 MILLION

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Lines of code in a Bentayga, the vast majority of which are written in proprietary computer languages. The Bentayga’s product-line director tells us that refining and debugging the software in a modern car can be the biggest task facing its developers.

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“The harness is delivered on a pallet that’s basically the size of the car,” says Peter Guest, Bentayga product-line director. “It’s so big and stiff, it’s not like an old-fashioned harness with flexible wires.” And there’s not just one standard Bentayga wiring harness. Each individual SUV gets a harness specifically built for it depending on its options load. In Bentley’s language, that means the harnesses are “bespoke.” But you’re probably not going to hear a salesman incorporate that into the pitch.

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90

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Number of control modules, or computers, communicating across the Bentayga’s local area network.

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Of course, the wires in modern vehicles don’t just illuminate lights or lower the windows; they also move volumes of information regarding powertrain performance, vehicle stability, cabin temperature, and so on. “It’s seven different networks, all working at different speeds,” explains Stuart White, module leader for the Bentayga’s electrical system. “And they all have different primary uses. But they’re all integrated together. The idea with the information is that it’s shared across everything. We don’t have one sensor for one function; each sensor feeds information into several different functions.”

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110

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Approximate weight, in pounds, of the wiring in a Bentayga. For comparison, Painless Performance, a company that builds wiring harnesses for restorations, tells us that a bare-bones muscle car’s harness weighs less than 10 pounds.

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In geek-speak, this type of network is called a digital multiplex bus system, and it’s the standard in virtually all cars today. It cuts down on the need for wire and relays by allowing signals for multiple systems to travel the same wires. Because as huge and complicated as the Bentayga’s electrical system is, it’s actually much simpler and lighter than it could be.

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