VSS valve accumulator
points

644_095

Key:
Electrohydraulic
control unit
(control valve assembly)

System pressure
Depressurized
Energized

Transmission Control Module
J217
36

De-energized

Function plan – 0CK/0CL transmission with park-by-wire
Data is exchanged between the selector
mechanism and the transmission via the
Gateway over the Infotainment CAN and
the FlexRay data bus – refer to page 70.

FlexRay
IN

Infotainment CAN

Key:
Selector
mechanism

G754 Transmission Fluid Temperature
Sensor 2– MTF temperature sensor
J217 Transmission Control Module
J587 Selector Lever Sensor System Control
Module
N486 Parking Lock Solenoid
– Parking lock holding magnet
V553 Transmission Electric Pump 2
– MTF pump

Gearbox

LIN

FlexRay
OUT

BP
BM

1

644_038

Selector mechanism

FlexRay Bus Plus
FlexRay Bus Minus
Starter control signal
(P/N signal)

Function
Selector Lever Sensor System
Control Module
J587

The parking lock is engaged mechanically by spring force
alone (P-ON). The parking lock module is disengaged
(P-OFF) by hydraulic pressure produced by the Mechatronic
unit. A special locking mechanism integrated in the piston
of the parking lock module additionally secures the parking
lock in the P-ON or P-OFF position and increases the operating reliability of the park-by-wire system. Refer to page 42.
The core of the locking mechanism is Parking Lock Solenoid
N486. N486 is activated by Transmission Control Module
J217. Selector Lever Sensor System Control Module J587
provides feedback to J217 on the actual status of N486. J217
and J587 communicate with one another bi-directionally via
the Gateway using the Infotainment CAN and the FlexRay
data bus.
The various functional states of the parking lock and the
parking lock module are shown below:

Parking lock module

Parking lock piston

3

1

2A 2B

1

Parking lock engaged (P-ON) – refer to illustration
644_095

4A 4B

4C

4D 4E

Starting scenario
The vehicle is shut off (the bus is at idle) and the parking
lock is engaged (P-ON).

Locking balls

Central ball
Parking lock
cylinder
Parking Lock
Solenoid N486
– Parking lock
holding magnet
644_077

The entire hydraulic system is depressurized and de-energized. When Solenoid Valve 6 N93 is de-energized, the inlet
from the parking lock cylinder to the oil sump is open. The
parking lock spring pushes the locking pawl into the tooth
gap in the parking lock gear and holds the parking lock in
the engaged position.
The parking lock holding magnet is inactive. The locking
balls do not have a locking effect because the central ball
does not exert any force on the locking balls.
37

2

Parking lock disengaged (P-OFF)
Selector Lever Sensor System Control Module
J587

2A

2B
Parking Lock Solenoid – N486
– parking lock holding magnet

2B
Transmission Control Module
J217

Solenoid Valve 6
N93

644_086

3

Keep parking lock disengaged by activating drive position N (time-limited P-OFF position – refer to page 31)1)

3
1)

Note: The parking lock module is
only depressurized in N after the
ignition is switched OFF. This is a
special function for workshop/car
wash scenarios. After N is selected
and the ignition is switched ON,
the system pressure is applied to
the parking lock module.

Key:
System pressure
Depressurized
Energized
De-energized

644_087
38

2A

Disengage parking lock (P-ON --> P-OFF)

To disengage the parking lock, Parking Lock Solenoid N486
is deactivated. Transmission Control Module J217 then
energizes Solenoid Valve 6 N93, which in turn directs the
system pressure to the parking lock cylinder. The piston
force is greater than the force of the parking lock spring.
The parking lock is disengaged. If the P OFF position is
detected by Drive Position Sensor G676, the parking lock
holding magnet is activated (refer to 2B).

Parking lock cylinder
Parking lock piston

Annular groove P-OFF

Locking balls

Central ball

Tappet with spring

644_088

2B

Keep parking lock disengaged (P-OFF)

In the P-OFF position, oil pressure is continuously applied
to the parking lock piston – refer to (3) for exception. To
safeguard against an unwanted pressure drop, the parking
lock piston is additionally locked with the aid of a locking
mechanism. This locking mechanism is actuated by Parking
Lock Solenoid N486, in turn was activated by Selector Lever
Sensor System Control Module J587.
Function – locking mechanism / parking lock holding
magnet
The armature is pulled into the coil by energizing N486.
The armature pushes the central ball upwards with the
tappet, with the result that the locking balls are pushed
into and held in the P-OFF annular groove as long as N486
is energized. To activate the lock, N486 is initially energized
by applying approximately 1.2 A. To hold the lock, the
current is reduced to approximately 620 mA. This prevents
the coil from overheating and reduces power consumption.

3

Coil

Armature

Parking Lock Solenoid – N486
Parking lock holding magnet

644_089

Keep parking lock disengaged by activating drive
position N1)

The P-OFF position can be maintained by selecting drive
position N before switching off the ignition or before shutting off the engine (bypassing the Auto-P function). After
switching the ignition off, Selector Lever Sensor System
Control Module J587 remains active in local run-on mode
and energizes Parking Lock Solenoid N486.
Transmission Control Module J217 shuts down as soon as it
has reduced the pressure inside the pressure accumulator
– refer to page 41 (4D). The P-OFF position is now held
solely by N486 or by the locking mechanism, which locks
the parking lock piston in the P-OFF position. This P-OFF
position is maintained for a limited time – refer to page 31
"Auto-P function".
644_090

39

4

Engage parking lock (P-ON --> P-OFF)

Starting scenario
Taking (2B) as a starting point – refer to illustration
644_089 – the engine is shut off when the vehicle is stationary and the parking lock is engaged by the Auto-P
function. The process of "engaging the parking lock" (up to
(1) on page 41) involves several steps (4A) – (4E).

4A

4B

644_092

644_091

4A

To engage the parking lock, the parking lock holding
magnet must first be switched off to allow movement
of the selector shaft.

Solenoid Valve 6 N93 is deactivated and opens the
inlet from parking lock cylinder to the oil sump. The
pressure in the parking lock cylinder is dissipated. The
parking lock is engaged (P-ON) by the parking lock
spring.

4E

4C 4D

40

4B

644_093

644_094

Parking lock engaged (P-ON)

Drive Position Sensor
G676

1

Solenoid Valve 6 – N93
VSS valve accumulator points

Solenoid Valve 6 N93 – de-energized
3

4
5

Key:
System pressure
Depressurized

6
1

2

Energized

644_096

644_076

De-energized

Solenoid valve 6 N93 – energized
3

4
5

6
1

2

1
2
3
4
5
644_097 6

System pressure from pressure
accumulator
To gear actuator control unit
To parking lock cylinder
To clutch control unit
To clutch control unit
To oil sump

4C

If the P-ON position is detected by Drive Position
Sensor G676, Selector Lever Sensor System Control
Module J587 energizes Parking Lock Solenoid N486.
This ensures the parking lock cannot be disengaged
because of a malfunction.

4D

The pressure in the pressure accumulator is now
actively reduced by alternately activating the gear
actuators. After the pressure has dissipated, J217
deactivates unless prevented from doing so by other
internal activity. Selector Lever Sensor System Control
Module J587 remains active and energizes Parking
Lock Solenoid N486.

4E

Solenoid valve 6 N93
Solenoid valve 6 N93 has two adjacent switch
positions.
• Energized switches the system pressure to
the parking lock cylinder.
• De-energized opens the inlet from the
parking lock cylinder to the oil sump.

N486 is energized by J587 until the Gateway goes to
sleep and deactivates J587. The parking lock is now in
the starting position (1) – refer to page 36 or
illustration 644_095.

41

Functional reliability of the parking lock
If the system malfunctions during vehicle operation, this
ensures that the parking lock is not engaged after a simple
fault.

The system is configured so the P-OFF position is maintained in two ways when not faults are present: first,
hydraulically by system pressure and second, electromechanically by Parking Lock Solenoid N486.

X

Y

644_099

644_098

X

If an unwanted drop in hydraulic pressure occurs in the
Mechatronic unit, P-OFF position is maintained by
Parking Lock Solenoid N486. Because N486 is
activated by Selector Lever Sensor System Control
Module J587, P-OFF position is maintained even if there
is a loss of electrcal power to the Mechatronic unit.

Y

In the event of a fault in the power supply to N486 from
J587, the P-OFF position is maintained electro-hydraulically by the Mechatronic unit.

Parking lock mechanism

P-OFF position
Parking lock spring

Sliding cone with spring

If the parking lock gear is as shown
here, the locking pawl can lock into
the tooth without resistance.

1
Thrust bearing, fixed

Pawl with spring

Parking lock gear

644_100
42

Drive Position Sensor G676
The position of the parking lock is monitored by Transmission Control Module J217 and Drive Position Sensor G676.
With shift-by-wire, the sensor signal is used only to determine the position of the parking lock.

For further information about G676, refer to the Audi Service
TV program: "7-speed dual clutch gearbox 0CK – S tronic
Part 2 – Service and practical advice for workshop personnel"
of 26.10.2014.

Sender element trim

Selector shaft

Sliding cone and spring are pre-stressed

P-ON position –
locking pawl engaged

P-ON position – locking pawl not engaged

2

3

644_101

Since the parking lock gear is "tooth to tooth", the sliding
cone does not push the locking pawl into the tooth until
the vehicle moves a little.

644_102

For safety reasons, the geometry of the parking lock gear
and the locking pawl gearing is designed so the locking
pawl cannot engage at a speed of over approximately
2 mph (3 km/h).

Note
The parking lock gear locks the pinion shaft of the front final drive. If the vehicle is raised on one side at the front, the
locking action is cancelled on the opposite wheel.

43

Emergency release
During normal operation, the parking lock is
electro-hydraulically actuated. To allow electro-hydraulic
disengagement of the parking lock, the engine does not
have to be running. This is because the 0CK/0CL transmissions are supplied with ATF by an electric-powered ATF
pump and a pressure accumulator. The ATF supply is not
dependent on operation of the engine. This means the
parking lock can be disengaged when the ignition is on.
To hold the parking lock in the OFF position, sufficient ATF
pressure must be available or the parking lock holding
magnet must have a sufficient power supply.

The emergency release mechanism of the parking lock
must be actuated in the following situations:
• To tow the vehicle
• If the parking lock cannot be released electro-hydraulically due to a malfunction.
• If the vehicle cannot be maneuvered or moved due to
low supply voltage.
• If the engine is not running and it is necessary to maneuver or move the vehicle, for example, in the workshop.
• For function testing after carrying out assembly work on
components of the emergency release mechanism.

In the event of malfunction, the emergency release mechanism is used to disengage the parking lock or to hold the
P-OFF position for longer, if necessary.

Lever for parking lock
emergency release

A special feature is the positioning of the emergency
release Bowden cable in relation to the gear selector lever.
A rigid rod and a mushroom-shaped plate are attached to
end of the emergency release Bowden cable and surround
the selector lever without touching it. This minimizes
structure-borne noise transmission from the transmission
to the Bowden cable, and into the passenger compartment.
The plate and the gear selector lever do not make contact
until the emergency release mechanism is actuated.
44

Attachment of the
emergency release cable
644_079

Installation location of the emergency release mechanism

Emergency-releasing the parking lock (P-OFF position)

In the Audi A4, the parking lock is emergency-released
from inside the vehicle by means of a cable pull. The emergency release mechanism is located under the cupholder in
the center console.

Warning! Before actuating the emergency release mechanism of the parking lock, the vehicle must be secured to
prevent it from rolling away.
The wrench and screwdriver needed for the procedure are
located in the vehicle tool kit. After removing the rubber
inlay, remove the cover using a screwdriver – refer to illustration 644_080. Items (1) and (2) show the procedure.
Rubber inlay

Cover

644_080

Socket wrench

2