Initial Inspection and Diagnostic Overview

General Information

CAUTION:
Before beginning repairs on the electrical system:
- Switch off all electrical consumers.
- Switch the ignition off and remove ignition key.
- Disconnect negative (-) battery terminal.
- Prior to disconnecting vehicle battery on vehicles equipped with Audi Telematics by OnStar(R), switch-off the emergency (back-up) battery for Telephone/Telematics Control Module J526.
- After reconnecting vehicle battery on vehicles equipped with Audi Telematics by OnStar(R),switch-on the emergency (back-up) battery for Telephone/Telematics Control Module J526.
- When disconnecting and reconnecting battery terminals, observe all applicable Notes and torque specifications, as well as instructions on performing OBD program and electrical system function checks as specified in.

Only use genuine Audi parts. Only then can trouble-free installation and optimal reception be guaranteed.

All Audi radio units are coded in the instrument cluster as part of the convenience system. It is not necessary to enter an "anti-theft" code subsequent to disconnecting and reconnecting the vehicle battery, removing and installing the existing radio or removing and installing the existing instrument cluster.

Before troubleshooting or servicing, technicians must be familiar with the functions and operation specifics of the applicable standard or optional radio system. Always read the radio owners manual and review all radio, tape player and CD player/changer functions.

NOTE:
- Additional information:
Owners Manual
Self Study Program - Course Number 991103 "2002 Audi A4 Technical Features"
Self Study Program - Course Number 991503 "The 2005 Audi A4"
Wiring Diagrams Component Locations
Antenna cable repairs.
CAN-Bus wire repairs

Retrofitting Radio Systems, notes
Factory-installed connections and wiring are compatible with genuine Audi radios only. Aftermarket radios using different types of connectors must be installed using appropriate adapters.

When connecting vehicle speed signal wire on radios with GALA function, take particular care to avoid short circuits as otherwise vehicle malfunctions could occur (e.g. engine management system).

Vehicle malfunctions may also occur if the vehicle speed sensor signal wire is connected to aftermarket radios, and damage to Scan Tools may occur when the Data Link Connector (DLC) K-wire is connected to aftermarket radios. Vehicle or Scan Tool damage caused by connection to aftermarket radios is not warrantable.

Retrofitting of aftermarket radios may affect Antenna Amplifier, since original Audi radio units have a remotely driven antenna (the voltage supply of the Antenna Amplifier is driven via a center wire of the high frequency cable). Where available/applicable, use a remotely driven adapter (vendor: Votex).

CD equipment retrofitting, notes
Depending on market, vehicles may be equipped with CD equipment cable preparation. CD prep cable and connectors can only be used with genuine Audi CD equipment.

Diversity antenna system, notes
Radio systems "Concert" and "Symphony II" use an antenna system with diversity function. This is designed to enhance and optimize reception quality.

In addition to the roof antenna or rear window antenna with amplifier, antennas with amplifier in rear window or side windows are used.

The individual antennas with amplifier are connected via the Antenna Selection Control Module J515 (diversity box).

The signal received by the radio via the antenna wire (HF) is checked and then sent out again by an additional antenna connection (IF).

Information about the test result is then passed on to the Antenna Selection Control Module J515. If the antenna signal is too weak, the control module switches to a different antenna (diversity function).

There are no visible or audible signs of the diversity switching process.

Radio System - "Symphony II BOSE(R))" with "Audio Pilot(R)", notes
From model year 2004, Audi A4 with Symphony II - BOSE(R) radio system use Inside Microphone R74 integrated with the front interior lamp module. The microphone is connected directly to Amplifier R12.

Amplifier R12 then adjusts the BOSE(R) sound settings according to changing interior noises. When noise increases in the interior, the amplifier automatically adjusts the volume according to the sound pattern.

The interior noises are minimized and the sound quality increases.

Microphone, checking. Testing and Inspection