Wiring Harness: Testing and Inspection

Diagnosis Of Fiber-Optic Cable Breakage

The MOST bus (fiber-optic cable) in the Touareg is responsible for data transmission between the components of the multimedia system. The MOST bus (fiber-optic cable) is connected between the individual devices in a circle, see the figure.

The MOST Bus Includes Following Components Of Radio Navigation System:






1 Instrument Cluster Control Module (J285)

2 MOST Bus (Fiber-Optic Cable)

3 Information Electronics Control Module 1 (J794)

4 DVD Changer (R161)

5 Digital Sound System Control Module (J525)

6 TV Tuner (R78)

• Not available in the USA or Canada.

7 Radio

8 Data Bus OBD Interface (J533)

9 Can Bus Line

10 CAN Bus line

This means that data input and data output for light signals occur at each module.

In every vehicle there is always only one fiber-optic cable, regardless of version.

When Is Ring Break Diagnosis Performed?

Ring break diagnosis is performed in the case of problems (customer complaint) or in the case of complete failure of the multimedia system.

What Can Cause A Ring Break?

Electrical malfunction, such as a malfunctioning fuse or voltage supply, cause a ring break. This can also be triggered by optical malfunctions such as:

• Malfunctioning control module receiver.

• Malfunctioning transmitter of the upstream control module.

• Malfunctioning transmission path (fiber-optic cable).

Where Is The Test Program In The Tester?

Automatic in the case of a DTC memory entry

Without a DTC memory entry:

- Press the Sprung button.

- Select "Function component selection".

- Select "body".

- Select "Electrical equipment".

- Select "OBD-capable systems".

- Select "J533 data bus on board diagnostic interface".