[angusgr]

> I think you were emulating the ABS module right? In that case, the spinning out of control is actually probably your fault. If you had not emulated this, the system would realise there is an ABS fault (from the messages not being present) and not use the ABS reported speed. It might even fall back to motor speed automatically.

That's a reasonable expectation, and this got left out of the follow-up post I linked, but in the "full car with wheels off the ground" tests we actually tried unplugging the brake module of an otherwise working car and it didn't change anything (including the gradual constant rpm increase in Neutral). If anything the behaviour might have gotten a little more aggressive with the brake module missing.

Have now observed similar behaviour for all three of "spoofed brake messages with 0 wheel speeds and emulated checksums", "fully operational car with wheels off the ground", and "car with wheels off the ground and ABS/brake module unplugged". ¯\_(ツ)_/¯

> Re: shaft scenario, if the motor shaft is broken the safety risk is pretty minimal because the torque wont actually cause the car to move. > > I guess this is what they arrived to in the FMEA.

Fair enough, that makes sense. I guess if that's the case then the other behaviour is outside of the scope of what they need to care about.

[aetherspawn]

If you lifted a working car off the ground and it did it anyway I’ll admit that I’m a little concerned. It should stop creeping around 15km/hr.

[angusgr]

If you're interested then click the link in my first reply (which is to a newer post). The first video shows the working car reaching 8000rpm (about 80km/h) around six seconds after the accelerator was released. The second video shows the speed creeping steadily from 38km/h to 44km/h (~2600rpm) after switching to Neutral (before we got nervous again and touched the brake).

(I don't really understand it, but I also haven't managed to think of a safety issue here for normal car use: the broken driveshaft is just a bit scary as the motor spins unloaded at >10,000rpm for a while. The only other time this seems likely to happen is if a mechanic puts the car in Drive on a hoist, and it'll stop as soon as they tap the brake.)

[dzdt]

Accident modes for car on a lift in a repair shop, or car gets high-centered with drive wheels in the air?