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Please read through all of the instructions here and make sure you understand them before attempting this procedure!

A common problem that plagues Audi 100 models and early A6 models is a faulty display on the Auto Check system. After years of trouble-free service, you might see symbols that are garbaged, or faults displayed that are not actually occuring such as a flashing 'Brake Light' warning or a cracked bulb icon. This document will describe how to repair the circuit board at little or no cost to fix these problems.

Definitions and Acronyms:

  • PCB: Printed Circuit Board


Tools Required:

  • Soldering iron and solder
  • Voltage meter
  • Phillips head screwdriver
  • Small flat head screwdriver
  • Rubbing alcohol and cotton swabs
  • Tweezers


Procedure:

  • There is a covering strip that goes along the bottom of the instrument cluster. On the bottom of this strip, there are two or three screws -- remove the screws and remove the covering strip.
  • This will expose three screws along the bottom of the instrument cluster that hold it in place -- remove them. When they are removed, you can remove the instrument cluster. It helps if the steering wheel is adjusted all the way down and all the way out, if you have an adjustable steering wheel. It may take a bit of work to fit the cluster around the steering wheel, but it is possible. It may help to reach around behind it and unplug the wiring connectors. Unplug all 6 connectors.
  • When the instrument cluster is out, carefully set it on its face and look at the back of it. You should see 6 small TORX screws that have a brass or gold color. Unscrew them and remove the white cover. This will expose the PC Board that you are repairing.
  • If your dash display is showing pictures incorrectly (with waves or missing pixels), read procedure 1. If your dash is showing warnings that it should not be showing, read procedure 2.

Procedure 1

Symbols are displayed incorrectly
In most cases, display corruption is caused by bad contacts in connector #1 (shown in the picture above). It is easy to remove the top half of the connector by gently rotating it horizontally a few times (as indicated by the red arrows). After releasing the plastic lock, you can pull the green connector cover off. Visually inspect the pins, clean them with rubbing alcohol, and use tweezers or a small pick to pry the pins to give better contact with the wires. Reassemble the connector when you are done.

Procedure 2

Random warnings are displayed
This is caused because the quality of this PCB is somewhat poor, and the components are not soldered to the board very well. Inspect the PCB carefully for cracks in solder joints. Pay special attention to the pins on the black connector (#2 in the picture). A bad solder joint will be easy to spot.
Resolder any pin that looks questionable, or just resolder them all -- better to spend the time now than have to remove the dash again later!


This procedure was written by Lt.Kubosh after many hours of lurking in his car. Questions/Comments about the procedure go to him.


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