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Comment by danmg | Hacker News Reader

When ABS systems fault, they just turn in to non-ABS brakes.

What's the worst that would happen with a malfunctioning active suspension system? It wouldn't lower when going highway speeds, so you'll get more drag.

The only computer that absolutely needs to work to keep your car running is the one that's controlling the EFI system. If that's not running well, it's pretty obvious since the engine will stall out. If you have a modern automatic transmission, then you'll need that one too, and that's pretty obvious if it's not working correctly. Everything else is an accessory, non-essential and part of planned obsolescence.

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ABS not working as intended could be a surprise to the driver and cause a crash, especially if you become dependent on it.

It's just like that AF 447 crash, they stalled from 38,000 ft to the ground because they never expected the computer to let them stall the plane.

But I mostly agree, the only software things I would see as absolutely life critical on a car would be drive-by-wire controls. All the rest will just either stall it, reduce performance or break something.

>especially if you become dependent on it.

Nobody is ever going to become dependent on locking up their brakes during normal driving. Power brakes would be dangerous if they failed because without them you get very substantially reduced braking but in no way would the lack of ABS be any more dangerous than driving a car without ABS to begin with.

An ABS failure could easily become fatal if it increased your stopping distance beyond what you'd achieve without it. After all it works by modulating the signal you send to the brakes.

That's irrelevant and it doesn't change the fact that no one drives with the intention to brake hard enough that ABS activates. There's zero chance of anyone becoming dependent on it.

My point is that ABS failure isn't equivalent to not having ABS at all - it can fail in a way that is actively harmful.

I'm not sure that's even possible. I could be mistaken but brakes are designed to be resilient to failure to the point that there aren't really any common single points of failure in a modern car. Brake circuits are actually kept separate from the master cylinder on down so that if one of the seals blows out on the master cylinder there's still another seal for the other circuit. If there's a cut in one of the brake hoses and the fluid leaks out, the brake fluid reservoir splits into two sections at the bottom so that even if one leaks to the point of being bone dry the other side still has some fluid left. The brake booster is designed so that it's a solid piece going all the way through it so if the brake booster is totally broken it works like a linkage. The brake booster is also designed with a check valve so that even after the engine is turned off you still have some vacuum stored in the booster for a couple presses of the pedal before the brake assist stops.

I'm not saying that there couldn't be a failure mode that would prevent someone from using the brakes but due to the attention to detail for everything else about the design and redundancy of the braking system on a car I think it's doubtful that the ABS actuator would be designed in such a way as to allow a software error or broken part to potentially prevent the brakes from working.

There is a lot of snow where I live and the ABS triggers all the time and yes some people just slam the brakes expecting their ABS to optimally slow down on ice.

Yep, and those people are dangerous idiots. Even with ABS it is improper to slam on your brakes on low-traction surfaces. The purpose of ABS is to prevent wheel locking under hard braking, but it is not intended to respond and recover from pure idiocy.

The correct way to apply the brakes is the same with or without ABS, you should always do it smoothly with increasing force as necessary. Doing this would allow ABS to function properly, and in the case of no-ABS, will allow you to feel and respond when locking may occur.

Even if your ABS were to fail, that does not absolve you of the responsibility of driving like a complete moron. It's an unfortunate reality that most of the people on the road in the US frankly should not be driving.

> ABS not working as intended could be a surprise to the driver

That's why there's a warning light for this

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