Why Modern Cars Need Master Switches

[Chetlaham]

I've been saying it for some time, but I do not believe in drive by the wire. At least not without master kill switches that drop electricity directly going to the ignition, drive motor and a gas shutoff ball valve in the fuel supply line. Along with a manual string driven backup emergency brakes.


My honest opinion is that drive by the wire malfunctions occur more than we are told about, and, it is only getting worse. Even with robust electronics there are still common mode and discrete mode software failures taking place that are impossible to simulate practically to the point in which they can be avoided in the real world.


https://www.carscoops.com/2025/08/m...e-to-stop-before-violent-crash-in-viral-clip/

Electronicification is a no-no for me.

 

[Chetlaham]

Ok so I updated the link because the Reddit one was taken down. My apologies ahead of time if this link goes down as well.

 

[donprohel]

First: electronics can be made very, very, very, very, "safe", but it is expensive and requires competence, experience and skills which are in very short supply on the market.

Second: cars are meant to be cheap, not to be safe; even the standard of automotive safety, the ISO 26262, is the most miserable standard ever seen and its main goal is to make it possible not to have competent, skilled and experienced people, because such people cost money; achieving safety is just an afterthought, a side effect.

Third: a "master switch", as you call it, is a good idea only for the cases where the so-called "idle current principle" is applied like the holy bible; this is the case of European railways, where no matter where you are, no matter what you are doing, no matter what is happening around you, if you interrupt the power supply you will never cause any damage; now think of a car suddenly braking in the middle of the highway...

 

[Chetlaham]

I feel it better than the engine stuck cruising at 60 MPH with no brakes, no steering and no shifting of any kind like the guy in the video.

The master switches would choke fuel to the engine by closing a ball valve on the supply line via a hard physical rod and another would physically disconnect the battery and alternator electrical feeding the ignition system. So no spark plugs, no fuel pump, ect. In an all electric car this would be a link to a high interrupting DC disconnect switch that opens all sources of power to the drive motor.

The car after such kill switch activation becomes powerless. It is moving on inertia, however the engine and/or motor can no longer keep outputting power. It can no longer keep that car at steady speed or accelerate it.

Next, when safe to do so the emergency brake can be pulled steadily like on an older car, the steal wire pulls on the brake pads steadily bring the car to a stop.

Ideal? No, but better than having the engine/motor keeping the car at a high rate of speed without deceleration.

 

[vacerator]

Once our previous 2020 Ford acted like it had a Master switch. We were at a restaurant in a congested dining, office and retail area. When we were leaving the dash said No key detected. Had to lay the key fob in the bottom of the console compartment and it started. You do the same if the fob battery is dead.