eSelf Study Program 970243

The 2015 Audi A3 Onboard Power Supply
and Networking Systems

• The Self Study Programme teaches a basic knowledge of the design and functions of new models, new
automotive components or new technologies.
It is not a Repair Manual! Figures are given for explanatory purposes only and refer to the data valid at the
time of preparation of the SSP.
For further information about maintenance and repair work, always refer to the current technical literature.

Note

Reference
2

Audi of America, LLC
Service Training
Created in the U.S.A.
Created 11/2013
Course Number 970243
©2013 Audi of America, LLC
All rights reserved. Information contained in this manual is based on
the latest information available at the time of printing and is subject to
the copyright and other intellectual property rights of Audi of America,
LLC., its affiliated companies and its licensors. All rights are reserved
to make changes at any time without notice. No part of this document
may be reproduced, stored in a retrieval system, or transmitted in any
form or by any means, electronic, mechanical, photocopying, recording
or otherwise, nor may these materials be modified or reposted to other
sites without the prior expressed written permission of the publisher.
All requests for permission to copy and redistribute information should
be referred to Audi of America, LLC.
Always check Technical Bulletins and the latest electronic service repair
literature for information that may supersede any information included
in this booklet.

Revision 1: 11/2013
3

Contents
Power supply....................................................................................... 6
Battery ....................................................................................................................................................6
Battery housing .....................................................................................................................................6
Fuses, relays and jump start terminal .................................................................................................7

Networking.......................................................................................... 9
Installation locations of control modules ...........................................................................................9
Topology ...............................................................................................................................................11
Overview of bus systems .....................................................................................................................13
New features of the bus system ........................................................................................................13
Optical data bus system MOST150 ....................................................................................................14
Special tool VAS 6778 .........................................................................................................................14

Control modules................................................................................15
Brief descriptions .................................................................................................................................15

Exterior lighting................................................................................29
Light switch ..........................................................................................................................................29
Headlights ............................................................................................................................................30
Headlight range control ......................................................................................................................32
Tail lights ..............................................................................................................................................34
High-mounted brake light ..................................................................................................................35
License lights .......................................................................................................................................35

eSelf Study Programs........................................................................36
Knowledge Assessment....................................................................38

4

This eSelf Study Program teaches a basic knowledge of the design and functions of new models,
new automotive components or technologies.
It is not a Repair Manual! All values given are intended as a guideline only.
For maintenance and repair work, always refer to the current technical literature.

Note

Reference

Power supply
Battery
The battery for the 2015 A3 is located in the engine compartment and is protected by a battery box. Battery size
and type are dependent on engine version, trim and country
specification. Standard batteries, EFB batteries and AGM
batteries are used.

In general, vehicles with gasoline engines are equipped
with an EFB battery, while diesel engine equipped vehicles
us an AGM battery.

EFB

AGM battery

An EFB (Enhanced Flooded Battery) can be regarded as a
heavy-duty wet-cell battery. The positive plate inside the
battery is coated with an additional polyester mesh. This
provides additional retention for the active battery material. The deep-cycle resistance is higher than that of conventional batteries. An EFB is charged in exactly the same
way as a conventional battery.

In AGM (Absorbent Glass Mat) batteries, the battery electrolyte is held within a microporous glass matting. In
addition to having higher deep-cycle resistance than an EFB
battery, the AGM battery is noted for its leak-proof construction. Special charging procedures may be required for
an AGM battery.

The following batteries are used in the 2015 Audi A3 dependent on engine type:

Standard batteries

EFB

AGM batteries

•
•
•
•
•

• 59 Ah/280 A
• 69 Ah/360 A

• 58 Ah/340 A
• 68 Ah/380 A

44 Ah/220 A
51 Ah/280 A
60 Ah/280 A
61 Ah/330 A
72 Ah/380 A

Battery housing
There are three different lengths of battery retaining points
to accommodate the different battery sizes.

Hole

Battery housing length

1

8.3 in (212 mm)

2

9.7 in (247 mm)

3

10.9 in (278 mm)

Hole 1
Hole 2

Hole 3

610_008
6

Fuses, relays and jump start terminal
Jump start terminal on the engine bulkhead

The positive terminal on the battery and the jump start
terminal on the engine compartment bulkhead are used for
charging the battery and jump starting.

Battery ground terminal and
Battery Monitoring Control
Module J367

Battery positive

Battery A
Fuse rail in the E-box with fuses
identified by “SA” in the Wiring
Diagrams.

E-box with fuses and relays identified by “SB” in the Wiring Diagrams.
610_073

Fuse holder and relay carrier under the instrument panel
with the designation “SC” in the Wiring Diagrams

In addition to standard fuses, the space-saving mini-fuses
and circuit breakers (thermal fuses), a new J-Case fuse is
being used. As with other fuses, they are identifiable by
their color.

Fuse rating

Color

20 A

blue

25 A

white

30 A

pink

40 A

green

50 A

red

60 A

yellow

A new gripping tool is used to remove and install the J-Case
fuse. It is stored in the cover of the E-box in the engine
compartment.

J-Case fuses

610_072

Gripping tool
for J-Case
fuses

610_071
7

Notes

8

Networking
Installation locations of control modules
Some of the control modules shown in the overview may be
optional and/or country specific equipment.

Always refer to the current service literature for complete
details about control module locations as well as instructions for their removal and installation.

J387

J668
J104

J250

J794

J500

R242
E380

J685

J428

J234

J587

J255

J431

J518

J745

J533

J743

J285

J527
J525

J764

J623

J667

J519
J386

9

Key:
E380 Multimedia System Control Head
J104
J234
J250
J255
J285
J386
J387
J428
J431
J492
J500
J518
J519
J525
J527

ABS/ESP Control Module
Airbag Control Module
Electronic Damping Control Module
Climatronic Control Module
Instrument Cluster Control Module
Driver Door Control Module
Front Passenger Door Control Module
Distance Regulation Control Module
Headlamp Range Control Module
All Wheel Drive Control Module
Power Steering Control Module
Access/Start Authorization Control Module
Vehicle Electrical System Control Module 1
Digital Sound System Control Module*
Steering Column Electronics Control Module

J533
J587
J623
J667
J668
J685
J743
J745
J764
J769
J770
J772
J794
J926
J927

Data Bus On Board Diagnostic Interface
Selector Lever Sensor System Control Module
Engine Control Module
Left Headlamp Power Output Stage
Right Headlamp Power Output Stage
Front Information Display Control Head
DSG Transmission Mechatronic
Cornering Lamp and Headlamp Range Control Module
Electronic Steering Column Lock Control Module
Lane Change Assistance Control Module
Lane Change Assistance Control Module 2
Rearview Camera System Control Module
Information Electronics Control Module 1
Driver Side Rear Door Control Module
Passenger Side Rear Door Control Module

R242 Driver Assistance Systems Front Camera

J927
J772

J769

J492

J770
J926

*Only on vehicles equipped with the Bang & Olufsen sound system option 9VS.

625_097
10

Topology
The topology shows all control modules with connectivity
to the data bus system. Some of the control modules
shown here are optional, country-specific equipment, or
will be introduced at a later date. Be aware that all the
modules shown will not be installed on every vehicle.
Light switch
E1

Headlight power
module, left
J667

Power Sunroof
Control Module
J245

Wiper motor
control unit
J400

Anti-theft Alarm
System Sensor
G578

Rain/Light
Recognition Sensor
G397

Alarm horn
H12

Headlight power
module, right
J668

Humidity sensor
G355

Power output
module for left
LED headlight

Vehicle Electrical
System Control
Module
J519

Power output
module for right
LED headlight

Instrument Cluster
Control Module
J285

Lane Change
Assistance Control
Module 2
J770

Steering Column
Electronics Control
Module
J527
Driver Side Rear
Door Control
Module
J926

Driver Door Control
Module
J386

Passenger Side
Rear Door Control
Module
J927

Front Passenger
Door Control
Module
J387

Data Link Connector
Multifunction
steering wheel
control unit
J453

Data Bus Onboard Diagnostic Interface
J533

Nox Sensor Control
Module
J583*

Access/Start
Authorization
Control Module
J518

Nox Sensor Control
Module 2
J881*

Electrical Steering
Column Lock
Control Module
J764

Passenger Occupant