TSB: Brake Pedal Travel Perceived as “Too Long” Just Before the Vehicle Comes to a Standstill - July 22, 2022

[submatrix]

my car has steel suspension and ive driven ones with air, what happens is, the wheel jumps up and looses contact with the ground for a sec and it gives that jumping feeling. don't feel it with the air suspension as much as it controls the rebound

I don't think a wheel losing contact with the ground would cause the car to jerk forward though?

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[Toodal00]

I don't think a wheel losing contact with the ground would cause the car to jerk forward though?

I had this issue with my 2018 E-class, had a shitty suspension and it would jump over bumps and jerk forward for a split second.

 

[cccmanhattan]

So my car is back at Porsche again, when I last got it back from the dealer in December and it started acting up again a few days later, they said Porsche engineering suggested the replace another part. Two months later, they reached out and said they had the part and I should bring it in. Since I hadn't heard from them and the problem returned, I had a different dealer bleed them again, although it turns out they're under the same ownership, have the same claim of missing a special machine to bleed the brakes and the problem returned a few days later.

It's now back withthe original dealer getting the new part (Hydraulic unit for ABS) installed, but to make matters worse, the heat stopped working on the way in and by all accounts that part is a month out.

All told, I'm 88 days and 5 visits in on this brake issue and if the heater is infact more than a month out, that pretty well puts me at 4 months out of the first 16 without the car.

I'm a bit at a loss because I really love the car, just can't responsibly keep money tied up in a car I can't drive. I've opened a case with Porsche NA and we'll see where that goes.

 

[Crick]

diagnostic tests by my Porsche SA, it was determined that the cause was attributed to a faulty brake booster

@YWGT3 Would you tell me which dealer and service rep you used in the bay area?

This is exactly the experience that I have. It is scary when it happens - having to run the brake pedal much farther than expected hoping the vehicle will stop. Not confidence inspiring.

Approaching a stop with light to moderate pedal pressure from normal speed. Then if one feathers the break peddle (lift a little to reduce the breaking action) to prevent premature stopping, the brake pressure is lost and one must depress the brake significantly farther (which can be 'to the floor') to stop the vehicle.

 

[YWGT3]

@YWGT3 Would you tell me which dealer and service rep you used in the bay area?

This is exactly the experience that I have. It is scary when it happens - having to run the brake pedal much farther than expected hoping the vehicle will stop. Not confidence inspiring.

Approaching a stop with light to moderate pedal pressure from normal speed. Then if one feathers the break peddle (lift a little to reduce the breaking action) to prevent premature stopping, the brake pressure is lost and one must depress the brake significantly farther (which can be 'to the floor') to stop the vehicle.

Contact the service manager, Gunter Feldmeier, at Fremont Porsche. His team was able to diagnose and fix the braking issue similar to what you're experiencing with your Taycan.

 

[cccmanhattan]

So my car is back at Porsche again, when I last got it back from the dealer in December and it started acting up again a few days later, they said Porsche engineering suggested the replace another part. Two months later, they reached out and said they had the part and I should bring it in. Since I hadn't heard from them and the problem returned, I had a different dealer bleed them again, although it turns out they're under the same ownership, have the same claim of missing a special machine to bleed the brakes and the problem returned a few days later.

It's now back withthe original dealer getting the new part (Hydraulic unit for ABS) installed, but to make matters worse, the heat stopped working on the way in and by all accounts that part is a month out.

All told, I'm 88 days and 5 visits in on this brake issue and if the heater is infact more than a month out, that pretty well puts me at 4 months out of the first 16 without the car.

I'm a bit at a loss because I really love the car, just can't responsibly keep money tied up in a car I can't drive. I've opened a case with Porsche NA and we'll see where that goes.

I should have updated this sooner, but I did eventually get this fixed, After replacing the booster and they Hyraulic unit and flushign the brakes again it finally (mostly) went away, but the pedal still drops and grabs the brake intermittentlywhen transitioning from regen to friction brakes at low speeds. I also had a massive lockup up the other day when driving on ACC, traffic slowed up quickly, I got the collision warning and jumped on the brakes and the front left locked up, left a massive stripe on the highway and filled the car with smoke.

 

[Jenner]

https://static.nhtsa.gov/odi/tsbs/2023/MC-10240398-0001.pdf

Brake Symptom – Brake Pedal Travel Perceived as “Too Long” Just Before the Vehicle Comes to a Standstill: Observe Specified Procedure (SY 90/21)

• Old software version in the PSM control unit

A new software version is available for the PSM control unit since June 16, 2023. This software update improves the functionality of the PSM hydraulic unit to optimize performance and enhance the brake pedal feel over a longer period of time.

2 weeks ago I dropped off my '21 Taycan Turbo S for the exact symptom above and gave them an older TSB from 2022. They were able to replicate the issue and went directly to Porsche Germany for guidance. They were told to load the new software but my PSM unit wouldn't take the new code. They had to order a new PSM unit, hopefully arriving any day now. Will post an update on how it feels after I get it back.

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