Total braking system failure?

[CertLive]

Glad you are OK. For a start shall we actually believe the OP for once in that he was unable to use the breaks. Quote: "Could not depress the pedal at all." " I definitely leaned in on the pedal, but it wouldn't budge." But yes if all the assists fail at larger effort you should be able to get some breaking.

3silverISgold it would be great to hear an update of what actually went wrong with the system to learn.

 

[Dangerous Fish]

Glad you are OK. For a start shall we actually believe the OP for once in that he was unable to use the breaks. Quote: "Could not depress the pedal at all." " I definitely leaned in on the pedal, but it wouldn't budge." But yes if all the assists fail at larger effort you should be able to get some breaking.

3silverISgold it would be great to hear an update of what actually went wrong with the system to learn.

The thing is, other than some foreign object getting under the pedal, or jammed somehow in the linkage, there is nothing in the braking system which could fail and lead to a solid pedal and no braking. I think we're all willing a accept there may have been a chance in a million that something really strange like that happened, but the balance of probability is that power assistance was disabled and the pedal just needed to be pressed harder.

I've read similar reports about the power assisted steering "locking up solid". When PAS fails, it may feel like you can't move the steering wheel, but there's a physical connection between the steering wheel and the rack, so you can still steer, albeit with a lot more effort.

Those of us who have had old, unreliable cars have experienced all this sort of behaviour at some point but that isn't necessarily the case with every driver these days.

 

[run-the-joules]

It wouldn't be a bad idea if every current driver swapped their lovely modern easy-to-drive car with a 1967 stick-shift Mustang for a day. They'd learn a lot about how cars work.

But before that, everyone should ride a motorcycle for a few months

 

[Sophias_dad]

Side note: When the kids were learning to drive, I told them all about the loss of steering and eventual braking assist if the engine stalls/fails while driving, and even had them turn the engine off(but not 'lock'!) while driving around a big empty parking lot so they could get a feel for the car in those conditions.

 

[Stellavator]

Right. I’ve had “total system failure” before (not in the Tesla) ... power steering and power braking suddenly going away. Alternator seized up and snapped the serpentine belt. It definitely takes some manual effort, that’s for sure. But the systems ARE mechanically connected, so without any power whatsoever, it’s still controllable.

I’ll argue that the Tesla is even better than almost any other system out there, as not only do you have the hydraulic braking, but there’s ALSO regenerative braking available. AND, the electric steering rack has redundant control as well on Model 3.

Sorry this happened @3silverISgold. It’s difficult but manual reversion of the braking system is available. If you’ve never driven without power braking before, it takes a surprisingly large amount of force ... but the hydraulics are all there and working - if they weren’t, your pedal wouldn’t be stiff, it’d be on the floor.

I too have had a power failure in an Acura while driving. The power steering and power brakes went out. I “couldn’t” press the brakes hard enough to slow the car and in a panic jammed the transmission into reverse. Why I didn’t pull the emergency brake is anyone’s guess. Like I said, panic. After some very loud noises, the car came to a stop. Honda/Acura agreed that the primary electrical fault was the issue and there was a recall on the car for that problem. They covered the repairs. Three transmissions later, it was finally running again (at no cost to me).

Anyway, my point is, that experience taught me that unpowered power brakes are different from non-power brakes. I am old enough that my first few cars did not have power brakes. I know how to stop a car with non-power brakes. Lots of dainty ladies could do it very effectively back then. It required effort, but not the same rock hard impossible feeling effort needed for a failed power brake system. I believe the mechanics are different. Power brakes are not simply a powered non-power brake system. While you can mechanically press them, the leverages are very different. They are not engineered to be easily functional without power, as the old non-powered systems were.

So maybe let’s stop trying to shame the OP for not being familiar with old style brakes. That’s just silly, and not productive.

 

[TestPilot]

I too have had a power failure in an Acura while driving. The power steering and power brakes went out. I “couldn’t” press the brakes hard enough to slow the car and in a panic jammed the transmission into reverse. Why I didn’t pull the emergency brake is anyone’s guess. Like I said, panic. After some very loud noises, the car came to a stop. Honda/Acura agreed that the primary electrical fault was the issue and there was a recall on the car for that problem. They covered the repairs. Three transmissions later, it was finally running again (at no cost to me).

Anyway, my point is, that experience taught me that unpowered power brakes are different from non-power brakes. I am old enough that my first few cars did not have power brakes. I know how to stop a car with non-power brakes. Lots of dainty ladies could do it very effectively back then. It required effort, but not the same rock hard impossible feeling effort needed for a failed power brake system. I believe the mechanics are different. Power brakes are not simply a powered non-power brake system. While you can mechanically press them, the leverages are very different. They are not engineered to be easily functional without power, as the old non-powered systems were.

So maybe let’s stop trying to shame the OP for not being familiar with old style brakes. That’s just silly, and not productive.

I totally agree, a non-powered braking system and a powered system with loss of power are totally different animals, as is also the case with non-powered steering and power steering with loss of power. But hey, everyone always knows better right?!

 

[mongo]

The thing is, other than some foreign object getting under the pedal, or jammed somehow in the linkage, there is nothing in the braking system which could fail and lead to a solid pedal and no braking.

Yes, there is. The ABS system has valves to disconnect the pedal/ master cylinder from the brakes (that's how it can release the pressure to stop a skid). If these values were engaged, the pedal would do nothing.

https://www.scienceabc.com/innovati...ock-breaking-system-technology-cars-work.html

I've read similar reports about the power assisted steering "locking up solid". When PAS fails, it may feel like you can't move the steering wheel, but there's a physical connection between the steering wheel and the rack, so you can still steer, albeit with a lot more effort.

Also an unlikely event, but the power assist motor could theoretically hold the rack in a fixed position.

 

[ucmndd]

The brake pedal felt like it was in a locked position at the top of its range. Could not depress the pedal at all.

Yeah, that’s not a thing.

 

[beachsideev]

There is some kind of actuator that physically moves the brake pedal when the car is holding. Maybe this was stuck and prevented the pedal from being depressed? The screen did say holding was disabled.

 

[Sam1]

If nothing else, I'm sure a lot of us just learned how to operate the emergency brake

I'm glad they're learning now, but what kind of an idiot operates any machine without learning how to use the safety features first?

Rhetorical question... They're the reason warning stickers are on lawnmowers that say "don't put your hand under the mower if it is running"

 

[subieworx]

I'd go for the brake booster as well. With multiple system failures, I think it's pointing towards the 12V battery.

I'd think more of the vacuum pump than brake booster.

 

[subieworx]

There is some kind of actuator that physically moves the brake pedal when the car is holding. Maybe this was stuck and prevented the pedal from being depressed? The screen did say holding was disabled.

That is the parking brake building pressure in the system which forces the pedal out and to be very hard.

 

[beachsideev]

That is the parking brake building pressure in the system which forces the pedal out and to be very hard.

Really? That is clever. I thought it was an actuator.

Thanks!

 

[mongo]

I'd think more of the vacuum pump than brake booster.

Model 3 brakes module is all electronic/ motor, no vacuum involved.
iBooster

 

[imola.zhp]

In my experience with non-Tesla's (we dont have ours yet) EV's go a bit nutty when the 12v dies. When you see any warning signs about a bad 12v, either directly or indirectly, change the 12v immediately.

 

[Gasaraki]

When my alternator went in my 2016 WRX and the battery died while driving, I lost power steering and braking was harder but I was totally able to steer and brake, just with more effort. The physical brakes in the Model 3 should be operating the same way as an ICE car so it's really hard for us to comprehend how this could have happened.

 

[Kevy Baby]

He didnt even use the normal braking system.
...
His brakes were likely completely fine he just needs to press them properly to slow the 2 ton sedan down.

Except the OP DID attempt to use the "normal" brakes as was clarified in post #4.

 

[zecar]

That is the parking brake building pressure in the system which forces the pedal out and to be very hard.

Yes, to compress any gas in the system. I assume that the emergency braking system simply runs the booster continuously. In racy cars this is sometimes done because the assumption is boiled brake fluid has created gas.

 

[mongo]

That is the parking brake building pressure in the system which forces the pedal out and to be very hard.

The parking brake is a separately actuated unit on the rear brake assembly. No commonality with the hydraulic brake lines.
The electronic brake booster can cause pedal movement when actuating the service brakes (in some cases the pedal make noise (may be S/X version only)).

 

[beachsideev]

The parking brake is a separately actuated unit on the rear brake assembly. No commonality with the hydraulic brake lines.
The electronic brake booster can cause pedal movement when actuating the service brakes (in some cases the pedal make noise (may be S/X version only)).

Mine makes a slight noise. That is why I noticed the pedal moving down when the car was stopped. Otherwise I never would have noticed it.