Symptom-based workshop manual

Service
90/21

ENU

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Brake Symptom – Brake Pedal Travel Perceived as “Too Far”: Observe Specified
Procedure (SY 90/21)
Change overview:
Release

Date

Change

0

09/17/2021

•

First publication

1

09/27/2021

•

‘Reduced braking system efficiency’ symptom removed.

2

07/22/2022

•

Update of possible causes

3

01/20/2023

•
•
•
•

Order types added
Update of further measures
Update of required parts
Update of Labor Operations

4

07/18/2023

•

New software version

5

02/09/2024

•
•
•
•
•
•

‘Hardware replacement’ action removed
Order types added
Labor operations added
Adjustment of brake fluid quantity
Adaptation of software versions to 0190 for all model years
“Perform functional test of the hydraulic unit” added to
procedure

Model Line:

Taycan (Y1A / Y1B / Y1C)

Model Year:

As of 2020 up to 2024

Concerns:

Brake system

Symptom:

The customer complains that the brake pedal travel is subjectively perceived as “too far”.

Possible
Causes:

•

Bedding-in routine not yet completed

The new brake must be ground in on new vehicles or after replacing brake pads. The vehicle will take over
this responsibility automatically by deactivating recuperation for a short time. The bedding-in routine can
be up to 1,000 km/ 620 mls, depending on driving style.
•

‘Brake Refresh’ function

The new ‘Brake Refresh’ function was introduced from model year M (2021). This function is used to
maintain the friction coefficient of the brakes. Recuperation is deactivated briefly during this time.

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Symptom-based workshop manual

90/21

‘Stiff Learning Routine’ function

During regenerative braking (recuperation), the electric braking torque of the electric machine has to be
replaced with the hydraulic braking torque of the wheel brakes (‘blending’) at least once during braking,
usually shortly before the vehicle comes to a standstill.
In order to eliminate longitudinal deceleration fluctuations and brake pedal irritations during ‘blending’, the
actual stiffness of the brake system must be known as accurately as possible to the control units involved
(Porsche Stability Management (PSM) and Electric Brake Booster (eBKV)).
If the ‘stiffness learning routine’ is activated automatically too rarely, the following causes may have been
present:
•
•
•

The vehicle has not been charged for a long time.
The temperature of the brake discs was > 100°C (212°F) when the learning process was attempted
and that of the brake callipers was > 55°C (131°F).
The front wheels were regularly turned in too far when leaving the vehicle.

•

Generally, pedal travel is longer when manoeuvring.

In order to improve the metering action of the brakes while parking, a smaller brake master cylinder (HBZ)
is installed in the Taycan compared with the PHEV vehicles, which extends the pedal travel in order to
ensure better metering when parking and manoeuvring. In addition, both brake circuits are opened fully at
speeds of < 12 km/h/ 7 mph for noise, vibration and other comfort reasons, which also results in longer
pedal travel.
•

Poor friction coefficient of Porsche Ceramic Composite Brake (PCCB) and Porsche
Surface Coated Brake (PSCB) compared to grey cast iron brakes in wet and/or cold
weather conditions.

This effect can adjust when switching from electric to hydraulic braking. This can result in a change in
brake pedal feel during braking with the same pedal pressure.
Action:

1

Check completion of braking routine.
The break-in routine must be completed. If the braking routine has not yet been completed, the
“active” error code “C1399F0 - Operating brake, Grinding-in process active” will still be visible in the
Porsche Stability Management (PSM) control unit.
Further information can be found in the ‘Braking’ section of the Owner’s Manual.  Betriebsanleitung

2

Carry out functional test of the hydraulic unit and, depending on the test result:
•

Bleed the brake system and re-program the PSM control unit.

or
•

Feb 9, 2024
Page 2 of 7

Replace PSM control unit, including hydraulic unit, bleed brake system and re-program PSM
control unit.

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Symptom-based workshop manual
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Generally, pedal travel is longer when manoeuvring.
The state of the art has changed and vehicle operation seems unfamiliar at first. The new functions
and corresponding behavior of the vehicle must be communicated to the customer. The Owner’s
Manual for the vehicle can be used here if necessary.  Betriebsanleitung

4

Poor friction coefficient of Porsche Ceramic Composite Brake (PCCB) and Porsche
Surface Coated Brake (PSCB) compared to grey cast iron brakes in wet and/or cold
weather conditions.
The state of the art has changed and vehicle operation seems unfamiliar at first. The differences
between the brake systems and their behavior in appropriate weather conditions must be communicated to the customer. Section: ‘Brake’ Betriebsanleitung

Required parts and materials as needed
Parts Info:

Required parts if the PSM control unit including hydraulic unit needs to be replaced.
Part No.

Designation
– Location

Number

9J1614095SY

 Hydraulic unit

1 piece

or
Only for vehicles with special conversions/installations in production (M-no. S1G)
9J1614095MY
Material:

 Hydraulic unit

1 piece

Required materials (usually already available in the Porsche Center):
Part No.

Designation
– Location

Quantity

00004321086

 Brake fluid, 30-liter/ 7.92 gal container
- Brake system

Quantity as required*

Information
*
Approx. 1.25 liter/ 1.32 qt of brake fluid is required for conventional bleeding.
Approx. 3 liter/ 3.17 qt of brake fluid is required to replace the hydraulic unit.
Approx. 4.5 liter/ 4.75 qt of brake fluid is required for bleeding in conjunction with the “wheel brake
rigidity offset” test.

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Symptom-based workshop manual

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Required tools
Tools:

•
•

•
•
•

P90999 - PIWIS Tester 4
Battery charger with a current rating of at least 90 A, e.g., VAS 5908 90-A battery charger. For
further information about the battery chargers to be used, see the corresponding Workshop Manual.
 Workshop Manual '270689 Charging vehicle electrical system and battery'
Charger for high-volt battery, e.g., VAS 681 003A - Charger for high-volt battery
VAS 6860 - Brake Filling and Bleeding Equipment
VAS 6122 - Engine plug set

Check hydraulic unit, replace if necessary, and re-program PSM control unit
Work Procedure: 1

Check hydraulic unit.
1.1

Connect and switch on the battery charger.

1.2