Reference
For more information about Driver Assistance Systems Front Camera R242, refer to eSelf-Study Program 970343, The 2015
Audi A3 Vehicle Electronics and Driver Assistance Systems.

35

Data bus overview
The overview shows some of the information exchanged via data bus.
ABS/ESP Control Module J104

Distance Regulation Control Module J428

Prefill brake system ← I
Warning braking ← I
Partial braking operations I and II ← I
Target braking ← I

Prefill brake system → O
Warning braking → O
Partial braking operations I and II → O
Target braking → O
Audible and visual warnings → O
Display "Audi pre sense" system malfunction → O

Driving speed → O
Wheel speed FR → O
Wheel speed FL → O
Wheel speed RR → O
Wheel speed RL → O
Brake pressure → O
TCS / ESP status → O
Activate hazard warning flashers → O
Longitudinal acceleration → O
Transverse acceleration → O
Rotation about vertical axis → O

Steering angle ← I
TCS / ESP status ← I
Accelerator position ← I
Brake pressure ← I
Wheel speed FR ← I
Wheel speed FL ← I
Wheel speed RR ← I
Wheel speed RL ← I

Vehicle Electrical System Control Module J519

Power Sunroof Control Module J245

Reversing light switch status → O
Close sliding sunroof ← I
Close sliding sunroof → O (to LIN user sliding sunroof control
unit J245)

Close sliding sunroof ← I
(LIN user of onboard power supply control unit J519)

Instrument Cluster Control Module J285
Audible and visual warnings ← I
Display "Audi pre sense" system malfunction ← I

Power Steering Control Module J527
Steering angle → O

Steering Column Electronics Control Module J527
Information Electronics Control Module 1 J794

Cruise control system status → O

Audi drive select set-up → O

Airbag Control Module J234

Engine Control Module J623

Seat belt buckle status → O
Passenger airbag status → O
Close side windows → O
Close tilt/slide sunroof → O
Electrical partial tensioning → O (to LIN users front left and right
seat belt tensioner control units, J854 and J855 respectively)
Electrical full tensioning → O (to LIN users front right and left
seat belt tensioner control units, J855 and J854 respectively)
Seat belt tensioning status → O

Accelerator position → O

Wheel speed FR ← I
Wheel speed FL ← I
Wheel speed RR ← I
Wheel speed RL ← I
Longitudinal acceleration ← I
Transverse acceleration ← I
Rotation about vertical axis ← I
Vehicle speed ← I
Brake pressure ← I
TCS / ESP status ← I
Accelerator position ← I
Audi drive select set-up ← I
Reversing light switch setting ← I
Steering angle ← I

Door Control Modules J386, J387, J926, J927
Close side windows ← I

Front left belt tensioner control units J854 (LIN user of airbag
control unit J234)
Electrical partial tensioning ← I
Electrical full tensioning ← I

Front right belt tensioner control units J855 (LIN user of airbag
control unit J234)
Electrical partial tensioning ← I
Electrical full tensioning ← I

609_062

Key:

Data bus in general
LIN bus

←I
→O

Data is received (input)
Data is sent (output)
36

Engines
1.8L and 2.0L TFSI engines
Technical feature overview

Cylinder head with Integrated Exhaust Manifold (IEM)

2.0L TFSI engine shown. The 1.8L TFSI engine
does not have continuously adjustable exhaust
camshaft timing.

Optimized thermal management

Engine Temperature Control Actuator
N493

37

Both the 1.8L TFSI and 2.0L TFSI engines for the North
American market will only have the FSI injection system.
The dual injection may be introduced at a later date.

Combined FSI/MPI injection

Friction optimization and lightweight design

609_156

Reference
For detailed information about the 1.8L and 2.0L TFSI engines, please see eSelf-Study Program 920243, Third generation
Audi 1.8L and 2.0L engines from the EA888 model family.

625_107
38

Diesel engines
2.0l Second generation TDI engine
Technical features

Cylinder block with integrated balancer shafts

609_041

Oxidizing catalytic converter and diesel particulate filter

609_042

Cylinder head with variable valve timing

609_043

39

Oil pump with integral vacuum pump

609_044

Active coolant pump

609_045

Intake manifold module with integrated charge air cooler

609_017

609_046

40

Engine/transmission combinations
1.8l TFSI engine

0CW

2.0l TFSI engine

0D9

2.0l TDI engine

0CW

Transmission designations:
0AH

Explanation of manufacturer designation:
Example: MQ350-6F

(MQ200_5F)

0AJ

(MQ200_6F)

M

Manual transmission

02S

(MQ250_6F)

D

Dual clutch transmission

02Q

(MQ350_6F)

Q

Transverse installation

0FB

(MQ350_6A)

350

Nominal torque capacity

0CW

(DQ200_7F)

6

Number of gears

0D9

(DQ250_6A)

F

Front wheel drive

A

All-wheel drive (quattro)

41

Notes

42

Power transmission
Overview
The drive train components of the 2015 A3 are based on
proven technology and include the new 5th generation
Haldex coupling on quattro models.
The installation position of the transmission has been
adapted to the modular transverse module (MQB) by modifying the transmission flanges and mounting points. The
original 6-speed dual clutch transmission 02E is now designated as the 0D9. It’s installation is inclined 12 degrees
further back than the 02E.

Rear axle drive 0CQ
Final drive

Rear axle
drive vent

Haldex coupling vent

All Wheel Drive Control Module
J492

Haldex Clutch Pump
V181

Haldex coupling

609_129
43

ITM for the 02S and 0D9 transmissions
Both 02S and 0D9 dual clutch transmissions are integrated
with the Innovative Thermal Management system for the
2015 A3 model line-up. The 02S is used in the 1.8L A3
Front Track model while the 0D9 is used in the 2.0L quattro
model.

Transmission Coolant Valve N488
−− Activated and diagnosed by the ECM
−− Energized: valve closed, open coolant circuit
−− De-energized: valve open, closed cooling circuit

The transmission cooling circuit is initially open during the
start phase of a cold engine. During this time, Transmission Coolant Valve N488 is energized when the ECM
switches the valve to ground. If there is enough heat
available for the engine and for heating the passenger
compartment, the valve is de-energized. The cooling circuit
is now closed and the ATF is heated to operating temperature by the engine coolant. The ATF temperature value is
transferred from the transmission to the ECM via the
Powertrain CAN bus. If the ATF has reached operating
temperature, valve N488 is re-energized and the cooling
circuit is open.

12V

Coolant feed

If the ATF temperature exceeds a permissible value, N488
is de-energized again. The cooling circuit is closed. Because
the engine coolant temperature is kept below the
maximum permissible ATF temperature in this case, the
ATF is cooled by the engine coolant.

Selector mechanism with emergency release.
For further information, refer to page 52.

Coolant return
609_130

12°

Selector lever cable for actuating
the parking lock

0D9 transmission

609_131

44

5th generation Haldex coupling
Component overview
The most notable feature of the 5th generation Haldex
coupling is a new pressure control system. The hydraulic
pressure required for the Haldex coupling is produced by a
pump with centrifugal governor. The new Haldex coupling
is 3.7 lb (1.7 kg) lighter than the 4th generation coupling.

An electric motor drives a six axial piston pump. The pistons
are pushed against an inclined thrust plate. When the
pump cylinder rotates, the pistons execute an axial stroke
and move the Haldex oil to the pressure side of the pump.

Axial needle bearing

Clutch cage
Thrust plate

Thrust plate

Clutch plate assembly

Axial needle bearing

Working piston with seals

Axial piston pump with integrated centrifugal governor
Centrifugal lever

Pressure side

Haldex coupling pump
V181

Axial piston

Thrust plate

Haldex Clutch
Pump V181
Suction side

Pump sump

Centrifugal force
control valve

609_132
45

Pump cylinder

All Wheel Drive Control Module J492
All Wheel Drive Control Module J492 exchanges data over
the Suspension CAN bus. Its software determines the
pump output based upon programmed characteristic
curves, which in turn generates the required hydraulic
pressure delivered to the working piston cylinder.
The electric motor of the pump is controlled with a pulse
width modulated 12 volts. Current input is also measured.

The hydraulic pressure is determined as a function of
current input based on the characteristic curves. If a higher
pressure is required, pump output is increased by pulse
width modulation of the voltage. To reduce the pressure in
the working piston cylinder, pump output is decreased. The
system is supplied power via Terminal 30 and is protected
by a 15A fuse.

Pressure relief valve
The Haldex unit hydraulic system is protected by a pressure
relief valve. It consists of a valve ball and steel spring. If a
hydraulic pressure greater than 638.1 psi (44 bar) develops, the spring force is no longer sufficient to hold the
valve ball in place. Its movement unblocks the relief port
and the Haldex oil is displaced to the suction side of the
axial piston pump.

609_133

Needle bearing

2-way connector

Drive hub
All Wheel Drive Control Module
J492
8-way connector

Oil sleeve

Housing

Pressure relief valve

Ball bearing
Snap ring
Ring seal

O-ring

Flange

Flanged nut

609_134
46

Oil supply / hydraulic diagram
The axial piston pump with an integrated centrifugal governor is driven by Haldex Clutch Pump V181. The centrifugal
force acting on the centrifugal levers of the controller
increases with axial piston pump speed. The valve balls of
the centrifugal force control valves are pushed down into
the valve seat more firmly. This increases the pressure
maintained by the valves. This design allows the system to
achieve outstanding pressure increase and pressure reduction times.

The hydraulic pressure supplied to the working piston is
controlled by varying the speed of Haldex Clutch Pump
V181. When the speed of V181 increases, the pressure to
the working piston increases. This in turn increases pressure to the clutch plate assembly allowing more torque to
be transmitted.
If the speed of V181 decreases, there is less pressure
supplied to the working piston and less torque can be
transmitted.

Working piston

Pressure relief valve

Clutch cage

Haldex Clutch Pump
V181

Pressurized oil supply
to the working piston

Pump sump

Thrust plate
Axial piston pump with integral centrifugal governor

Centrifugal force control valve

Centrifugal lever

609_135
47

Operation - low pump motor speed
At low speeds, there is no pressure build-up inside the
working piston cylinder. Due to the low speed of the pump
motor, the centrifugal levers do not apply pressure to the
valve balls.

The pumped oil flows back into the sump through the
centrifugal force control valves of the centrifugal governor.
Color key:
Vacuum
Un-pressurized
Oil overflow

Clutch plate
assembly

pressure < 638.1
psi (44 bar)

Working
piston

Pressure relief valve

Centrifugal
lever
Centrifugal
force

Centrifugal force control valve

Centrifugal governor and
direction of rotation