ABS module failed - brakes failed

[Jamesfawcett]

My Taycan has gone in for failed brakes this week. 20k miles. I've had odd noises from the front for a while now and a vibration, but I also had uneven contact patterns showing on the front disks.

The dealership instructed me to brake more to clean the brakes when I sent over photos, but on a recent long trip I lost all brakes on a few occasions - foot to floor and only regen slowing me down. Quite scary when coming off the motorway and trying to come to a stop! Seemed to work better if you pumped the brakes a few times. I assumed it was from the brakes being cold but it got worse quite quickly.

I jacked up the car and spun the wheels and the front brakes were binding slightly, I sent this to my OPC and they said to have it recovered to them:

Had it recovered this week and it's been diagnosed a failed ABS unit.

I was going to post this on the the Complete brake failure thread but I don't think mine is caused by a brake fluid leak so probably unrelated.

I've got an on/off buzzing/vibration I've been chasing through the steering on mine for a year now, and the OPC have found two of my wheels slightly buckled, so I'm hoping that one of these is the cause when I get the car back - fingers crossed.

Other than that the OPC have been great so far at diagnosing it quickly.

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[d00d]

I'm going to familiarize myself with the emergency brake, since learning about your and Clive's serious problems.
Another issue we may face is sudden decrease in braking with wet disks when the hydraulics kick in at low speed.
Almost hit a charging station post in the rain because of that.

 

[Jamesfawcett]

Me too d00d! I assumed mine was wet brakes or just cold, the PCCB are usually terrible the first time I use them on any drive. I live at the top of a hill and I'm used to the first stop taking more pedal press but after that they seem good.

95% of my journeys in the Taycan my young children are in the car though so I'm hoping I don't need to use the emergency stop with how harsh it sounds. I've just had my rear handbrake calibrated too on my last visit to the dealership which I don't want to affect, as the cost for that calibrating was just under £100.

 

[Tooney]

I don't know if it applies but a TSB about PSCB brakes was issued in Oct. 2022: https://static.nhtsa.gov/odi/tsbs/2022/MC-10225839-0001.pdf

There are other brake-related noise TSBs you can search for in TSB list maintained by @rs38: https://ti-list.azurewebsites.net/

 

[Andics]

Can anyone point at any resources explaining what is the emergency break?

 

[Jamesfawcett]

Can anyone point at any resources explaining what is the emergency break?

Take a look at page 2 here it has some screenshots from the manual explaining: https://www.taycanforum.com/forum/threads/complete-brake-failure.19839/page-2

 

[Scandinavian]

Can anyone point at any resources explaining what is the emergency break?

It is described in the manual in the MyPorsche app. Check the manual under Vehicle Details. There you should find manual. In the search function type in brakes and browse through that.

 

[Murph7355]

....
The dealership instructed me to brake more to clean the brakes when I sent over photos, but on a recent long trip I lost all brakes on a few occasions - foot to floor and only regen slowing me down. Quite scary when coming off the motorway and trying to come to a stop! Seemed to work better if you pumped the brakes a few times. I assumed it was from the brakes being cold but it got worse quite quickly....

Interesting, and with Clive's note and the campaign on brakes that went out (long pedal) slightly worrying that maybe Porsche do have an architectural issue here.

What speed were you going when you had total loss?

The system is "brake by wire" AIUI, and at anything over 10mph, maybe less, it uses regen (at a much greater force than lift off regen)....so in theory you shouldn't lose braking at higher speeds (with foot to floor, you'd just expect it to brake harder at higher speeds).

 

[Jamesfawcett]

It happened when coming up to traffic after exciting the motorway and slowing down, I'd say a bit above 10mph but slowing down, maybe when it kicks over to the brakes? It's the same feeling when the PCCB are cold on that first time braking out of the garage (although you might tell me now that's not normal either!). Foot to floor, slowly coming to a stop, like when your brakes need bleeding in an old car, or badly setup drum brakes.

Either way the I've just had an update and the part arrives tomorrow at the OPC and they're putting me in a loaner Taycan from Monday so I'm happy!

 

[tigerbalm]

Was it all wheels or just the driver front that had that noise? Do you have any concerns that the very expensive discs could be damaged?

I'm paranoid about my PCCB discs!

 

[Jamesfawcett]

Was it all wheels or just the driver front that had that noise? Do you have any concerns that the very expensive discs could be damaged?

I'm paranoid about my PCCB discs!

I am a little concerned about permanent damage actually - but I also do trust this dealership they have been awesome. They're really thorough and I'm sure they will test them.

I looked back and it was March that I sent the images of my front disks, but I don't use the car that often. This is how they looked, but I think it's just part of the pads not touching the disk, and the lighter patches are just the "uncleaned" part of the disks I think, it soon polishes off by hand. I think this will be resolved when I get my car back with the new ABS pump.

@Tooney thanks for that TSB above - I did send that to my service advisor back when I sent these images in (in the same email as the images infact) but she confirmed that TSB doesn't apply to PCCB.

 

[tigerbalm]

This isn't the best photo – and I'll take a closer look at mine later today. But i do not notice that wear/colour difference on mine. They are consistent across the diameter of the discs.

 

[Murph7355]

It happened when coming up to traffic after exciting the motorway and slowing down, I'd say a bit above 10mph but slowing down, maybe when it kicks over to the brakes? It's the same feeling when the PCCB are cold on that first time braking out of the garage (although you might tell me now that's not normal either!). Foot to floor, slowly coming to a stop, like when your brakes need bleeding in an old car, or badly setup drum brakes.

Either way the I've just had an update and the part arrives tomorrow at the OPC and they're putting me in a loaner Taycan from Monday so I'm happy!

This is definitely when the car is switching between regen and brakes.

The tech bulletin on this is meant to sort it (brake line flush and bleed) but I'm far from convinced.

I've still felt inconsistency in the pedal after this bulletin was applied. It's always stopped before a ding though, so not sure it's down to them not working, more confidence.

(I was going to be glib and note that at least any accident would be at 10mph or below.... But plenty of damage could still be caused)

 

[Jamesfawcett]

Got my car back today - rapid turnaround! I had a brand new loaner Taycan in the meantime too.

My brakes are working perfectly now - better than ever, and the contact patches on the disks are perfect with no marks.

ABS pump was replaced and coded in, along with a full brake clean and brake fluid service.

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