Self Study Program 646 – Audi A4 (Type 8W)

VAG SSP 646. The Self Study Programme teaches a basic knowledge of the design and mode of operation of new models, new automotive components or new technologies. The Audi A4 (type 8W) is the second representative of the MLBevo (Modular Longitudinal Platform evolution) after the Audi Q7 (type 4M). A fully equipped Audi A4 (type 8W) has around 90 control units on board, many of which exchange data with one another. Such close co-operation would not be possible without an entirely new electronics architecture compared with the Audi A4 (type 8K) – especially when it comes to the driver assistance systems.

The new FlexRay bus system in the Audi A4 networks multiple control units and ensures that data is transmitted extremely quickly and securely. The key components are the engine, the automatic gearbox, the central suspension control unit, the Electronic Stability Control (ESC) system, the power steering control unit, the Stop&Go adaptive cruise control system including traffic jam assist, the video camera and the airbag control unit which manages the safety systems.

There are further data networks in addition to the FlexRay bus. CAN bus systems (CAN = controller area network) integrate the air conditioning system and several assistance systems such as Audi side assist and the surround cameras.

They also facilitate communication between the comfort/convenience control units, the infotainment modules and central display and operating components such as the MMI and Audi virtual cockpit.

So-called LIN buses (LIN = local interconnect network) complement the CAN buses by serving less complex subscriber systems such as the interior lighting.

The Bang & Olufsen Sound System with 3D sound uses a MOST bus (MOST = media oriented systems transport). As in other Audi models, the Audi A4 now also has aluminium high-current wires with diameters of 16 mm2, 35 mm2 and 50 mm2.

However, the Audi A4 is the first Audi to use aluminium wires with diameters of 2.5 mm2, 4 mm2 and 6 mm2. Thanks to these modifications, the electronics in the new Audi mid-range models contribute to a lightweight design. The weight of the vehicle in this area has been reduced by 6 kg compared with the previous model.

Learning objectives of this self study programme:

Once you have completed this self study programme you will be able to answer the following questions:

  • Where are the fuse and relay panels located in the Audi A4?
  • In what locations are electrical components fitted on the car?
  • Which bus systems are used in the Audi A4?
  • What are the tasks of the control units in the car?
  • What are the versions of the exterior lighting, and how are the individual light functions implemented?
  • What are the changes with regard to headlight range adjustment and calibration of the Audi Matrix LED headlights?


  • Voltage supply
    • Car battery
    • Jump start terminal
    • Supply structure
    • Fuses and relays
    • Aluminium wires
  • Networking
    • Installation locations of the control units
    • Topology
    • Bus systems used on the Audi A4
  • Control units
    • Brief descriptions
  • Exterior lighting
    • Headlight variants
    • Xenon headlight
    • LED headlight
    • Audi Matrix LED headlight
    • Dynamic turn signal function
    • Tail lights
    • High-level brake lights / number plate lights
  • Audi drive select
    • Functional characteristics
    • Displays and operation
    • Audi drive select function
    • Functional features
  • Vehicle electronics
    • Interior lighting
    • Overhead module
    • Anti-theft alarm
    • Central locking
    • Sensor-controlled luggage compartment release
    • Garage door opener (HomeLink)
    • Head-up display
  • Appendix
    • Self study programmes

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. This content is not updated.
For further information on maintenance and repair work, always refer to the current technical literature.

Language: English
Format: PDF
Pages: 72

Self Study Program 646 – Audi A4 (Type 8W) Vehicle electrics and electronics PDF free online