Here's How Brake-by-Wire Works, and Why It's Perfectly Safe

Brake-by-wire systems are becoming increasingly common for a variety of reasons. These systems are particularly useful in hybrids and EVs, where they allow the brake pedal to control both regenerative and friction braking, but even non-electrified cars—like the new C8 Corvette Stingray—use brake-by-wire, too. So, how do these systems work, and what happens if they fail?

As reliably as the sun rises and and sets, YouTuber Jason Fenske of Engineering Explained, is here to make sense of brake-by-wire. Fenske focuses on the system in the new Audi e-Tron Sportback, but he told Road & Track that all brake-by-wire systems are broadly similar.

Essentially, a brake-by-wire system controls the brakes electronically. A position sensor monitors how far the driver has pushed the brake pedal, which is used to determine the amount of braking force requested. A control then unit determines how much hydraulic pressure is required, and an electric pump is used to actually generate that pressure and stop the car. All of which happens in an instant. In some electric cars, like the e-Tron and Porsche Taycan, the brake hydraulics are only activated after a certain threshold is met—light pressure on the pedal may only trigger electric motor regeneration.

These systems allow brake pedal feel to be tailored to certain drive modes. Or as with the new Acura NSX, as brake temperature increases—when temperature increases, the pedal goes long, as it would with a conventional hydraulic system. Neat stuff, though you might be wondering what happens if any of the electronics fail. As Fenske explains, these systems maintain a physical connection between the pedal and the brakes themselves. If something goes wrong, a valve opens up that bypasses all the electronics, leaving you with a conventional hydraulic system.

So, there's no need to be afraid of brake-by-wire. And oftentimes, it's hard to tell the difference between a conventional hydraulic setup and brake-by-wire. For more, be sure to watch Fenske's video.

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Senior Reporter

A car enthusiast since childhood, Chris Perkins is Road & Track's engineering nerd and Porsche apologist. He joined the staff in 2016 and no one has figured out a way to fire him since. He street-parks a Porsche Boxster in Brooklyn, New York, much to the horror of everyone who sees the car, not least the author himself. He also insists he's not a convertible person, despite owning three.