Owner experiences steering and brake failure

[JBee]

If we could think of it, for these critical components, There's noway Tesla enginers would overlook it, otherwise it would be open for class action lawsuits.

One doesn't exclude the other, Tesla is not above failure or poor design.
Neither does Tesla have the monopoly on common sense.
They admit to it all the time, it's just that they call it "progress".

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[rbalkun]

It's called a "Critical Failure" not Catastrophe.

You are being blinded by the fanboi propaganda, just stick to the technical items. There's pages here on the forum discussing the issue in detail.

Your statements and terminology highlight the actual issue at hand, that you believe Tesla is better than any other manufacturer and can "never" do anything wrong.

That is the opposite of reality, they are failable just like anyone else and these successive failures should not be dismissed offhand, especially seeing there are more than one type of failure that are making these happen.

The consequence of them failing whilst driving is potentially catastrophic and should not be taken lightly, regardless of how the media are reporting on them.

Further just because they "share" a similar name does not mean they have the same standards as used in FbW in aircraft.

I can call a frog a prince, but neither have similar traits or capabilities.

So to have a conversation about it requires an understanding of how it actually works, with that we can try to understand what went wrong instead of just throwing one liners on the credibility of media, which btw, I also believe don't deserve my endorsement.

From my understanding there are three sets of sensors for redundancy, and two sets of motors with their own set of sensors on the front axle. The rear axle only has one motor.

The steering wheel is connected to a rotating actuator that also provides force feedback from the steering rack sensors. The only connection between the steering wheel and actuator to the steering rack are digital signals from the sensors. The sensors on the steering send the commanded steering angle to the controller, and the controller interprets that to the corresponding steering angle on the rack according to the current vehicle velocity.

Likewise the rack sensors transfers the rack position back to the steering wheel force feedback actuator so the driver can sense which angle the wheels are pointing in, and road undulations, traction etc.

Now if the steering wheel actuator fails then you will have a very light steering wheel without the force feedback, but the redundant sensors, if still powered, can send steering angle commands to the steering rack. That would not be that bad, seeing you can still steer, but it would be like driving a remote control car.

If the Steering wheel sensors fail, you have no input in controlling the steering of the vehicle. That would normally mean the rack if still functional would go to neutral and straight ahead, and if it's not working, remaining at that angle until the steering self straightens because of the wheel toe in angle.

So the critical safety items here are that the steering wheel sensors and the steering rack motor(s) work and are powered, and they give the rack the commanded steering angle. The front rack still works with just one motor, the second one is just in case the other doesn't, but both are used all the time.

So having multiple sensors going from the steering wheel to the rack means that a whole bunch of failure modes can be overcome. You could for example lose 2 sets of steering wheel sensors, the steering wheel actuator and a rack motor, and the steering will still work.

This leaves the power supply. Without the power supply there are no sensors, actuators or rack motors, so it is super crucial that these systems always remained powered no matter what.
For that reason the PCS (Power Conversion System) on the CT uses multiple DC to DC converters from the main pack to make 48V (at least 2) and also a separate 48V battery that can provide power should the DC converters or the main pack fail. This also provides power to the other vehicle accessories, like opening the doors and running electronics and contactors to connect the main pack etc.

Many of the errors accompanying the Critical Failure are in regards to the power system failing. In some it's been the DC Converter, others the wiring harness (unplugged or damaged cables doesn't help either).

The problem here is that various different fixes for the same resulting issue is not a good sign overall, of the design choices they made. If it was one reason, we could maybe blame a single component failure, but as it is it looks like there is a wider systemic problem at play.

This could be something trivial as the wrong calculations were used to specify the connector or cable rating, or there are voltage spike from another device somewhere else along the same 48V bus that runs through the whole vehicle. There are a huge amount of local DC converters on the nodes powering locks/windows/pumps etc all of which could have a design problem that could manifest itself somewhere else in the bus. Even the audio system is running on that bus and being fed by the PCS/48V supply at some point.

The question here is how well are those critical steering and braking systems isolated from all the rest. Until now neither have been specifically located just at the steering or PCS. That means that system isn't isolated well enough and something is causing the power failures on multiple systems, which defeats the purpose of having redundant power systems.

You spent more time writing out that response than I actually care ?

 

[HaulingAss]

You spent more time writing out that response than I actually care ?

I know, it's gotten pretty ridiculous.

Any fault is turned into a scary and dangerous situation, without even knowing any details except the truck decided it wasn't safe to drive and threw up some errors on a critical system. The way redundancy works is failure of one item will warn you to pull over and not drive anymore because it is no longer safe (redundancy is gone).

Sure, it sucks if it interupts your trip, but then we have the peanut gallery clowns surmising it must have been so scary and dangerous without a shred of evidence that it was either. ?

 

[Amuma]

Just a few more kinks they need to workout with this revolutionary 48v system.

 

[mark555055c]

We're going to hear every single story of every single cybertruck that has a hiccup or fault. The news agencies and negative folks out there won't have it any other way.

What have there been, maybe 10-15 that have had to be looked at by service? Less than 1%, that is for sure.

New cars have faults more often than folks think. It's just not normally plastered on the news, and customers typically are not tweeting at the CEOs of other car companies when their car needs service.

There is no story here.

 

[cgladue]

There is no statistical data for steer by wire on trucks. All I’m saying is if this is a genuine failure of steer by wire, it’s important to look into it instead of saying the odds of getting hit by lightning are the same. No it’s not. Failure rate of Steer by wire on Cars is not known, and we cannot compare the stats with airplanes. Planes have a completely different level of quality checks.

Nobody said anything about comparing it to planes. Of course planes are completely different. No o e is saying it shouldnt be looked i to. But what I was saying is it's not such a huge issue and life threatening situation as it was made out to be. Of course it's not good and of course it's dangerous but it's being trumped up just a little bit.

 

[CybertruckCovers]

The part written about "rusting body panels" and "disintegrating tires" does make make me question the validity of the article. I'd like to know more about what actually happened, though and wish there was more information about it. That's why I shared the article in the first place.

 

[rudedawg78]

you can still steer to the side of the road its not like you loose all steering and braking

Per the article, all steering and braking failed. So unsure if you still have the capability to steer to the side of the road, especially with steer-by-wire.

 

[JBee]

You spent more time writing out that response than I actually care ?

There were a few others that liked it, so no loss.

I think you got a different perspective at least, not everything is clear cut at first glance.

It's just as important to see the technical failure without the media filter, otherwise everything will become irrelevant.

 

[JBee]

I know, it's gotten pretty ridiculous.

Any fault is turned into a scary and dangerous situation, without even knowing any details except the truck decided it wasn't safe to drive and threw up some errors on a critical system. The way redundancy works is failure of one item will warn you to pull over and not drive anymore because it is no longer safe (redundancy is gone).

Sure, it sucks if it interupts your trip, but then we have the peanut gallery clowns surmising it must have been so scary and dangerous without a shred of evidence that it was either. ?

You only say that because you don't have the expertise to comment on the way it works technically. At least I'm in the peanut gallery, not sitting outside on the curb without a ticket to get in on the action. ?

 

[g7bupw9z]

How does the Steer by wire steering work on the Cybertruck?

It is not mechanically connected.

Also on power failure the brake booster also does not work.

This is not good by any definition of the word safe.

"It'll never replace the horse!" - Probably what horse-drawn carriage makers said about cars. Today's skepticism about steer-by-wire echoes a similar fear of change. Let's embrace the possibilities!

 

[CyberCowboy]

There were a few others that liked it, so no loss.

I think you got a different perspective at least, not everything is clear cut at first glance.

It's just as important to see the technical failure without the media filter, otherwise everyrhing will become irrelevant.

Well said JBee! I identify as a Tesla fanboi but this issue is very concerning to me. You clearly have an engineering background and I appreciate your detailed response. Tesla needs to address this (I'm sure they will) but it irks me that some people seem to believe that this is a "non-issue". I own and have owned many Tesla's and I'm a bit of an "active" driver, so the thought of ANY steering/braking malfunction is horrifying! Maybe the article was a little misleading and the owner's experience wasn't life threatening, but then again, I wasn't in the vehicle. Again, any malfunction that affects my ability to steer a vehicle safely warrants the highest level of attention. I will be following this topic closely...

 

[JBee]

"It'll never replace the horse!" - Probably what horse-drawn carriage makers said about cars. Today's skepticism about steer-by-wire echoes a similar fear of change. Let's embrace the possibilities!

In this case you might have your cart in front of your horse though.

Feel free to find and read all of my posts on this forum on different threads in regards to the Critical Failure.

For the record, brake and steering failure should not happen together as they should be on seperate systems. Both are a safety risk. It could of been lethal, so no joking matter. There are other similar failures by other owners being reported.

 

[agordon117]

Honestly, the position of "you shouldn't want to know", "tesla is smart, they would never let anything go wrong", "all investigation or questioning is FUD"... it's pretty annoying.

"oh there was no safety issue because this time it failed while it wasn't being driven"

Oh, great, so you're telling me you know without a doubt that it's impossible to lose power while you're driving? And that it's impossible for one system failure to cause another? No? Then shut up. Nobody is fear mongering anything. It should be known how new technology is set up to fail or to resist failure. The possibility of an electrical failure and having no power redundancy on the steer by wire is not a small issue. Being unable to steer to the side of the road is a concern, and it warrants investigation. Stopping in the middle of the highway is unsafe, so if a person wants to have a discussion about how many layers of redundancy prevent that (if any), then they should feel free to do so.

Tesla talked a lot about the redundancy in the steer by wire system in various interviews, but it seems that the redundancy is on the angular position of the wheel. Not on the power system. And given that there have been more than a negligible amount of power failures, some explanation is warranted.

 

[HaulingAss]

Per the article, all steering and braking failed. So unsure if you still have the capability to steer to the side of the road, especially with steer-by-wire.

Actually, the article doesn't say that "all" steering and braking failed suddenly, simply that these critical systems, at a minimum, threw error codes and stopped working. We don't know if they went into "limp mode" first or not, whether it's a software glitch or hardware failure or anything else.

All we know is it left the owners needing a ride. And people are jumping to big conclusions in an irresponsible manner.

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