Complete brake failure !!

[W1NGE]

Sounds like a failure of the manual brakes, not the regen braking. I've had that happen in ICE cars I've owned, only two in the almost 60 years I've been driving. One was caused by a master cylinder failure the other by a broken brake line. Once the cars slowed down I was able to stop them with the emergency brake.

It sounds like something similar where the regen braking slowed the car as it would normally but when you got below the threshold where the manual brakes take over they failed. I wonder what the equivalent of an emergency brake is on an EV?

Press and hold "P"

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[BigBob]

I wonder if hitting the regen button on the steering wheel would help bleed of speed relatively quickly. Though I guess in an emergency, experimentation probably not advisable.

regarding getting your car seem, If it was recovered under warranty by Porsche assist then the dealership is contractually obligated to inspect the car within a few days. From memory it is 5 or 7. So don’t accept the dealership fobbing you off. My experience with 2x (safety but fairly low risk) recoveries was getting the car back and fixed in a week or so. If I’d have gone via service booking it would have been 6+ weeks before they look at it.
A call to Porsche assist or maybe Porsche Reading (if you can find the right person) might help get the ball rolling.

Sounds very scary. Hope your Mrs is over it.

 

[WuffvonTrips]

my22 taycan turbo - 66k miles
...
car opc serviced and owned from new

How recent was its last service and was that its 3rd?

 

[Clive]

From posts on here and the Porsche Manual about 90% of braking is from the electric motors, regen braking. If my meter isn't lying, most of the time when I stop from speed the manual brakes don't kick in until I'm almost stopped. I'm sure this would be a bit different during an emergency stop but by how much I have no idea.

Still, even at a slow speed, it is disconcerting when you can't completely stop your vehicle. I was lucky that the two times it happened in my ICE cars I was able stop safely.

I'll be interested if they can isolate what caused the issue. The mechanical brakes aren't normally used all that much so you wouldn't think it would be caused by wear and tear on a car that new.

I wonder what would happen if you pushed the Park button while still moving? I'm not going to try it but maybe someone else has.

i can confirm that while trying to move the car to a safe place that without mechanical brakes working the pedal goes right to the floor and even at very low speed it ability to stop with regen alone is very low - so low it couldn’t even be safely driven onto the recovery trailer without fear of driving through the recovery truck cab !

this was beyond doubt a potentially fatal failure

 

[Clive]

How recent was its last service and was that its 3rd?

3rd service was last November - opc serviced to schedule from new

 

[Clive]

I wonder if hitting the regen button on the steering wheel would help bleed of speed relatively quickly. Though I guess in an emergency, experimentation probably not advisable.

regarding getting your car seem, If it was recovered under warranty by Porsche assist then the dealership is contractually obligated to inspect the car within a few days. From memory it is 5 or 7. So don’t accept the dealership fobbing you off. My experience with 2x (safety but fairly low risk) recoveries was getting the car back and fixed in a week or so. If I’d have gone via service booking it would have been 6+ weeks before they look at it.
A call to Porsche assist or maybe Porsche Reading (if you can find the right person) might help get the ball rolling.

Sounds very scary. Hope your Mrs is over it.

she won’t drive this car again - regardless of outcome re Porsche it’s going to have to be sold.

a terrifying experience for her that you just can’t ignore, she has no confidence in the Taycan whatsoever now

 

[W1NGE]

i can confirm that while trying to move the car to a safe place that without mechanical brakes working the pedal goes right to the floor and even at very low speed it ability to stop with regen alone is very low - so low it couldn’t even be safely driven onto the recovery trailer without fear of driving through the recovery truck cab !

this was beyond doubt a potentially fatal failure

This is truly shocking - I naïvely thought that all cars had a redundant system in case of catastrophic failures such as this.

I worry that this is another component sourced in a hurry from a non regular supplier due to the situation in Ukraine which impacted other parts (cables and trim) which were originated there. Your car is MY22 (so not old by any stretch) but within the window of when parts were scarce and alternative sources sought with perhaps not the requisite QA.

Keen to learn the diagnosis and prognosis thereafter.

 

[Clive]

OP, if you feel it was as serious as your posts suggest, you should call police at the time and file accident report and lmk what happened so there is an official report on record. Then you can take that report to Porsche and the appropriate government agency

police won’t be interested as there wasn’t an accident - the gov vehicle safety unit linked will be however, i will be in contact with them today

this shouldn’t happen on 3 yr old cars - the more i think about it the more i think porsche have a massive problem here and need to establish cause QUICKLY

 

[WuffvonTrips]

I wonder whether the emergency brakes (either triggered autonomously by collision sensors or by the "P" button) would still be effective if the hydraulics fail.

 

[Clive]

I wonder whether the emergency brakes (either triggered autonomously by collision sensors or by the "P" button) would still be effective if the hydraulics fail.

i guess it would be as it’s separate calipers i think ?

however it’s rear wheels only i think so like pulling a handbrake turn at 70mph ………….. which would be rather interesting !

 

[Scandinavian]

I wonder whether the emergency brakes (either triggered autonomously by collision sensors or by the "P" button) would still be effective if the hydraulics fail.

I think the parking brake is by Electric actuators. Seems also to be stated in the quoye from the manual.
’There is a sound like that when You engage the parking brake at stand still.

 

[Scandinavian]

sorry to hear this and happy that nobody got hurt or any damage done. Scary situation though.

The use of the emergency brake was pointed out to me by the Porsche Guru when we test drove the Taycan, as well as on handover. The same was done by the Tesla engineer when we collected our Tesla. He pointed this out strongly when driving with Autopilot engaged, as a safety feature.

But maybe this was done by those dealers only??

The next question is, would you have remembered all of that in such a horrible situation when the brake pedal hits the floor??

 

[W1NGE]

sorry to hear this and happy that nobody got hurt or any damage done. Scary situation though.

The use of the emergency brake was pointed out to me by the Porsche Guru when we test drove the Taycan, as well as on handover. The same was done by the Tesla engineer when we collected our Tesla. He pointed this out strongly when driving with Autopilot engaged, as a safety feature.

But maybe this was done by those dealers only??

The next question is, would you have remembered all of that in such a horrible situation when the brake pedal hits the floor??

Pretty sure that all cars with an electrically operated parking brake (normally a pull up button) performs the same role across many (if not all) manufacturers - has to really given there is no "handbrake"

 

[WuffvonTrips]

i guess it would be as it’s separate calipers i think ?

however it’s rear wheels only i think so like pulling a handbrake turn at 70mph ………….. which would be rather interesting !

Another potential limitation- I assume that the emergency auto braking is only triggered when it senses the car is about to drive in to something, it won't intervene to stop the car crossing the path of oncoming traffic (though maybe some of the optional assistance systems add such a capability).

 

[Clive]

Pretty sure that all cars with an electrically operated parking brake (normally a pull up button) performs the same role across many (if not all) manufacturers - has to really given there is no "handbrake"

at least you can feather in a manual handbrake gradually - an electrical one is surely on or off which at speed would be rather dramatic and result in a spin quite likely

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