DRAFT
Technical Information

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25/21

ENU

WMB1

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WMB1 - Re-Programming High-Voltage Battery Control Unit (BMCe) (Workshop Campaign)

Important:

:CRITICAL WARNING - This campaign includes steps where control unit(s) in the vehicle will be
programmed with the PIWIS Tester. The vehicle voltage must be maintained between 13.5 volts and 14.5
volts during this programming. Failure to maintain this voltage could result in damaged control unit(s).
Damage caused by inadequate voltage during programming is not a warrantable defect. The technician
must verify the actual vehicle voltage in the PIWIS Tester before starting the campaign and also document
the actual voltage on the repair order.

Model Year:

2021

Model Line:

Taycan (Y1A)

Concerns:

High-voltage battery control unit (BMCe)

Information:

Optimized software is available for the high-voltage battery control unit (BMCe) in the Taycan.
This software update prevents incorrect calculation of the state of charge (SoC) of the high-voltage
battery. Incorrect calculation of the state of charge can reduce the range in some cases.

Action required: Re-program the high-voltage battery control unit (BMCe) using the PIWIS Tester with test software version
39.900.075 (or higher) installed.
Affected
Vehicles:

Only vehicles assigned to the campaign (see also PCSS Vehicle Information).

Required tools
Information
The Taycan (Y1A) is equipped as standard with a lithium starter battery.
Lithium starter batteries must only be charged using a suitable battery charger that has a current
and voltage-controlled charge map.
For further information about the battery chargers to be used, see  Workshop Manual '270689
Charging battery/vehicle electrical system'.
Tools:

•
•

Battery charger with a current rating of at least 90 A and a current and voltage-controlled
charge map for lithium starter batteries, e.g. VAS 5908 Battery charger 90 A
9900 - PIWIS Tester 3 with test software version 39.900.075 installed

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Preparatory work
NOTICE
Fault entry in the fault memory and control unit programming aborted due to low voltage.
•

Increased current draw during diagnosis or control unit programming can cause a drop in voltage, which
can result in one or more fault entries and the abnormal termination of the programming process.



Before starting control unit programming, connect a suitable battery charger with a current rating of at
least 90 A to the vehicle.
NOTICE

Control unit programming will be aborted if the WiFi connection is unstable.
•

An unstable WiFi connection can interrupt communication between the PIWIS Tester and the vehicle
communication module (VCI). As a result, control unit programming may be aborted.



During control unit programming, always connect the PIWIS Tester to the vehicle communication module
(VCI) via the USB cable.
NOTICE

Control unit programming will be aborted if the driver's key is not recognized
•

If the driver's key is not recognized in the vehicle, programming cannot be started or will be interrupted.



Position the driver's key with the back facing forward upright between the holding struts in the rear
cupholder (emergency start tray) to ensure a permanent radio link between the vehicle and remote
control.
NOTICE

Programming interrupted
•

Malfunctions in control unit

•

Risk of damage to control unit



Route the line between the vehicle communication module (VCI) and diagnostic socket on the vehicle
without tension and make sure that the connector is inserted fully into the diagnostic socket.



Check that the rechargeable battery for the PIWIS Tester is charged sufficiently. Connect the PIWIS Tester
to the power supply unit if necessary.

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Information
The procedure described here is based on the PIWIS Tester 3 software version 39.900.075.
The PIWIS Tester instructions take precedence and in the event of a discrepancy, these are the
instructions that must be followed.
A discrepancy may arise with later software versions for example.
Work Procedure: 1

Remove plenum panel cover  Workshop Manual '85221901 Removing and installing (front)
plenum panel cover'.

2

Observe general instructions for isolating the vehicle from the power supply prior to performing
maintenance tasks  Workshop Manual '2X00IN Isolation from power supply prior to performing
maintenance tasks on BEV vehicles'.

3

Isolate the high-voltage system from the power supply  Workshop Manual '2X00IN Isolating
high-voltage system from power supply/Starting high-voltage system'.

4

Connect a suitable battery charger, e.g. Battery charger 90A, to the jump-start terminals in the
luggage compartment and switch it on.

5

Position the driver's key with the back facing
forward upright between the holding struts in the rear
cupholder (emergency start tray) to guarantee a
permanent radio link between the vehicle and remote
control  Emergency start tray.

6

Connect 9900 - PIWIS Tester 3 to the vehicle
communication module (VCI) via the USB cable.
Then connect the communication module to the
vehicle and switch on the PIWIS Tester.

7

Establish operational readiness (switch on ignition).

8

On the PIWIS Tester start screen, call up the 'Diagnostics' application.

Emergency start tray

The vehicle type is then read out, the diagnostic application is started and the control unit selection
screen is populated.

Re-programming high-voltage battery control unit (BMCe)
WARNING
Electrically moved side windows and rear spoiler
•

Danger of limbs being trapped or severed

•

Risk of damage to components

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

Do not reach into the danger area.



Keep third parties away from the danger area.



Do not move components or tools into the danger area.

Work Procedure: 1

Re-program high-voltage battery control unit (BMCe).
The basic procedure for control unit programming is described in the Workshop Manual 
Workshop Manual '9X00IN Basic instructions and procedure for control unit programming using the
PIWIS Tester'.
For specific information on control unit programming during this campaign, see the table
below:
Required PIWIS Tester software version:

39.900.075 (or higher)

Type of control unit programming:

Control unit programming using the 'Campaign'
function in the Additional menu on the PIWIS
Tester by entering a programming code.

Programming code:

K5N6Y

Programming sequence:

Read and follow the information and instructions
on the PIWIS Tester during the guided
programming sequence.
Do not interrupt programming and coding.
A backup documentation process for the
re-programmed software versions starts as soon as
programming and coding is complete.

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Programming time (approx.):

6 minutes

Software version programmed during this
campaign:

1441

Procedure in the event of abnormal
termination of control unit programming:

Repeat control unit programming by entering the
programming code again.

Procedure in the event of error messages
appearing during the programming
sequence:

 Workshop Manual '9X00IN Basic instructions and

Following control unit programming, the software
version can be read out of the high-voltage DC
charger (booster) control unit in the 'Extended identifications' menu using the PIWIS Tester.

procedure for control unit programming using the
PIWIS Tester - section on "Fault finding"'.

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Concluding work
Work Procedure: 1

Read out and erase the fault memories of all control units.
1.1

Press •F7“ in the control unit selection screen ('Overview' menu) to call up the Additional
menu.

1.2

Select the function “Read all fault memories
and erase if required” and press •F12“
('Next') to confirm your selection  Erasing
fault memories.
The fault memories of the control units are
read out.

1.3

Once you have read out the fault memories,
check the fault memory entries.
Erasing fault memories
Information
If control units are found to have faults that are not caused by control unit programming,
these must first be found and corrected. This work cannot be invoiced under the
workshop campaign number.

1.4

Press •F8“ to delete fault memory entries.

1.5

Press •F12“ ('Yes') in response to the question as to whether you really want to delete all
fault memory entries.
The faults stored in the fault memories of the various control units are deleted.
Information
If fault memory entries for individual control units cannot be deleted, proceed as follows:
•

End operational readiness (switch off ignition).

•

Disconnect the PIWIS Tester diagnostic connector from the diagnostic socket.

•

Lock the vehicle using the driver's key and remove the driver's key from the
proximity of the vehicle (approx. 10 meter/ 33 ft).

•

Wait approx. 15 minutes before unlocking the vehicle again.

•

Restore operational readiness (switch on ignition).

•

Plug the PIWIS Tester diagnostic connector into the diagnostic socket again and restore
communication with the vehicle.

•

Read out the fault memory again and delete any fault memory entries that are stored.

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Technical Information

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Once you have erased the fault memories,
select the 'Overview' menu to return to the
control unit selection screen  Control unit
selection.

Manually retract the rear spoiler, which extended
automatically during programming.
2.1

Select the 'Rear spoiler' control unit in the
control unit selection screen ('Overview'
menu) and press •F12“ ('Next') to confirm.

2.2

Control unit selection
Once the rear spoiler control unit has been found and is displayed in the overview, select the
'Maintenance/repairs' menu.

2.3

Select the function ‘Teach rear spoiler’ and press •F12“ (‘Next’) to confirm.

2.4

Read the instructions and confirm by pressing •F12“ ('Next').

2.5

Meet the displayed conditions that must be checked manually and tick the relevant 'Status'
box.

2.6

Select the Teach rear spoiler function and press •F8“ ('Execute') to confirm.

2.7

Once the rear spoiler has been taught and retracted fully, select the 'Overview' menu to
return to the control unit selection screen.

3

End operational readiness (switch off ignition).

4

Disconnect the PIWIS Tester from the vehicle.
Information
Connect the PIWIS Tester to a network as soon as possible and log into the PPN in order to transfer
the backup documentation created during this campaign to the PAG systems.

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5

Switch off and disconnect the battery charger.

6

Start the high-voltage system  Workshop Manual '2X00IN Isolating high-voltage system from
power supply/Starting high-voltage system'.

7

Enter the campaign in the Warranty and Maintenance booklet.

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Warranty processing
Information
The specified working time was determined specifically for carrying out this campaign and may differ
from the working time published in the Labor Operation List in the PCSS.
Scope 1:

Working time:
Re-programming high-voltage battery control unit (BMCe)
Includes:
Connecting and disconnecting battery charger
Connecting and disconnecting PIWIS Tester
Isolating vehicle from power supply and commissioning
vehicle
Reading out and erasing fault memories
Retracting (teaching) rear spoiler

Labor time: 96 TU

 Damage Code WMB1 066 000 1

Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training
courses. They are written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special
tools may be necessary in order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the
safe operation of your vehicle, and may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and
safely. Part numbers listed in these bulletins are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a
discrepancy, the work procedures in the PIWIS Tester are the ones that must be followed.

© 2021 Porsche Cars North America, Inc.

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