Audi A8 2019 Service Training page 37

ATF supply and hydraulics
In Mild Hybrid Electric Vehicles (MHEV), the 0D5 transmis-
sion is supplied ATF by two ATF pumps; one mechanically
driven pump on one electric pump. Both pumps draw the
ATF from the ATF intake filter.
Transmission Fluid Auxiliary Hydraulic Pump 1 V475 now
allows the TFSI engine to be shut off under coasting.
Mechanically driven ATF pump
This ATF pump is identical to the twin stroke vane pump
used in the 0BK transmission. It is powered by a chain drive
via the torque converter of the TFSI engine. When the
pump reaches a specified speed of approximately 500 rpm,
it provides a reliable supply of ATF with the auxiliary
hydraulic pump.
Transmission Fluid Auxiliary Hydraulic Pump 1 V475
By assisting the mechanically driven ATF pump, V475
provides a reliable supply of ATF for the start-stop func-
tions of the transmission.
If the auxiliary hydraulic pump is unable to circulate ATF
because the overload cut-out has been actuated or a fault
has occurred, the start-stop functions are no longer avail-
able.
If V475 is faulty, the yellow transmission
warning lamp lights up.
V475 operates within an ATF temperature range of 68 -
257 °F (20 -125 °C) and has three output levels. It commu-
nicates with Transmission Control Module J217 via a LIN
bus.
The auxiliary hydraulic pump provides a reliable and quick
supply of ATF. This aids disengagement of the parking lock
and allows delay-free start-up. If the mechanically driven
ATF pump reaches the required speed and is capable of
supplying system pressure by itself, the auxiliary hydraulic
pump receives a signal via LIN bus to stop circulating ATF.
Pump drive hub with spline,
connection to torque converter
Impeller shaft
Chain drive
Pump electronics – integrated into housing
Ground contact for voltage supply
Terminal 30, positive contact
to power supply
Connection, pressure
side
ATF suction filter
Brake A
Sun gear shaft S1/S2
ATF pump,
mechanically driven
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LIN bus connector
Brushless
DC motor
G-rotor pump with non-return valve
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