Resolved - Braking Issue/PSM Failure, with Video

[irrelevant]

Short description of issue...primarily while feathering the brake pedal near the end of a deceleration to achieve a smooth stop, a "croaking" sound is made. Brake pedal feel is inconsistent. No need to watch the entire video...the sound is present throughout, though worse or better at times. At 9:20, a PSM caution message is presented, and the regenerative braking appears to be unavailable. After this occurs, the brakes operate normally, without this annoying noise.

Our Taycan has had this issue for a couple weeks, but I hadn't driven it for over a week before yesterday afternoon (my wife has been driving it during that time). The issue seems to have gotten significantly more noticeable. We have a similar blended regen/mechanical braking system in our e-tron, so I'm familiar with how it should blend seamlessly.

I'll call the service department once they open.

Question....does everyone's Taycan make that "thunk" sound when transitioning from the brake pedal to the accelerator?

Thanks in advance. I'll update as more information becomes available.

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[tchavei]

Disclaimer: haven't picked up my own taycan yet.

When I test drove a 4S last December, I'm 110% sure it didn't do anything even near that sound. Not even that "blop" at the end so either I'm a master at smooth braking (lol) in a new, unknown car or that unit didn't do that. I was very attentive to all noises and feel as I had never driven an EV or even automatic before.

 

[irrelevant]

Thanks. I don't recall hearing anything like this from our test drive, but that was a year ago. I know our Audi doesn't display any of this behavior.

 

[Hirschaj]

I’ve had 2 CT4 and neither have made those sounds.

 

[irrelevant]

I’ve had 2 CT4 and neither have made those sounds.

Thank you.

 

[WattTurbo]

Just watched your video and mine makes the same noise when it's cold and regen has not kick in yet. So, this usually occurs while I am still getting out of my subdivision, and when it happens the green power bar does not get lit, which confirms it's using the brakes and not the regen. But, on yours the green power bar is definitely lit, but it only makes that noise when it's below say 5 mph. Maybe, the regen on yours stop and the brakes kick back in when it's below a certain speed. I don't notice that effect on mine though, or at least I never noticed it.

 

[irrelevant]

Just watched your video and mine makes the same noise when it's cold and regen has not kick in yet. So, this usually occurs while I am still getting out of my subdivision, and when it happens the green power bar does not get lit, which confirms it's using the brakes and not the regen. But, on yours the green power bar is definitely lit, but it only makes that noise when it's below say 5 mph. Maybe, the regen on yours stop and the brakes kick back in when it's below a certain speed. I don't notice that effect on mine though, or at least I never noticed it.

Thanks for sharing. Something definitely isn't right. The service department has the video for review. The PSM caution was an unexpected event that seems related, given the brakes operate traditionally, without noise, after the PSM failure. Hopefully catching that on the video will assist with troubleshooting.

I've not felt the Taycan's brakes have been...confidence inspiring, since we took delivery, so perhaps this problem has been present in some form from the beginning of our ownership six weeks ago, and has gotten progressively worse over time. Our e-tron displays none of this unnecessary drama/inconsistent pedal feel when braking using regeneration or transitioning to mechanical brakes.

 

[Leverage]

Definitely not normal behaviour & sound.
On another note, yesterday after some heavy rains, I had my left brake that made a quacking sound when I started the car. Sounded like the brake was "stuck" on its pad. I had to hard press the brake & then it was gone so nothing similar to your problem.
Better send it directly to the dealer.

 

[Tooney]

A number of Porsche TSBs issued about brake noise, this is the latest one: https://static.nhtsa.gov/odi/tsbs/2023/MC-10233885-0001.pdf

 

[irrelevant]

Thanks. None of that seems to apply to this issue. This isn't a brake pad/rotor issue. It very much seems the noise is coming from under/behind the dashboard or from the firewall area, and may be originating from the master cylinder.

 

[dtich]

It seems, and I'm just extrapolating anecdotally, that the Taycan braking system, being an odd combo of mechanical and recuperation, is particularly susceptible to proper bleeding and to glazed pads, which are a greater occurrence because of the nature of the system (recuperation braking requiring much less mechanical braking so the pads lightly drag on the rotor for much more of the pad's lifespan)....

Maybe I'm totally off base, but there are too many common occurrences of this type of issue (including the clunk issue, and the wet brakes issues) for it not to have some systemic origin.

As always, P needs to re-evaluate their software relating to braking systems. There seem to be use cases, while uncommon, that trick the system into misbehaving. Honestly, I bet some machine learning in the braking system could hunt these issues down. But, that's another subject....

2¢

And OPs particular case may indeed be a failed component. But, I'd bet it's not unrelated.

 

[T-Fury]

I’m not certain but this thread may be relevant. Reminds me of a breaking issue and noise I had with my turbo…

https://www.taycanforum.com/forum/threads/there’s-a-goat-stuck-in-my-front-brakes.8523/

 

[irrelevant]

I’m not certain but this thread may be relevant. Reminds me of a breaking issue and noise I had with my turbo…

https://www.taycanforum.com/forum/threads/there’s-a-goat-stuck-in-my-front-brakes.8523/

Thanks for sharing. I'd have never thought to use the keyword "goat".

I got an insulting e-mail from the service advisor that read this is normal, and "brake squeal" is to be expected. I had to wait a few moments to cool down before responding.

I didn't realize in error I'd checked the option box for "service department that assumes you're a moron".

 

[T-Fury]

Sorry to hear about the hassle. They were able to fix this issue with my car and it remained fixed afterward fortunately. Best of luck!

 

[RehobothTaycan1]

I had a similar issue and it was the brake module. once replaced that fixed the issue.

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