Audi Repair: 1998 Audi A4 Avant quattro, gas gauge, power regulator

Question
The speedo, tach, gas gauge stopped operating.  Other items in the instrument cluster work.  Replaced fuses but no results.  Is there  a relay I should check?  If so, which one.

Thanks,


Answer
On the back of the instrument cluster is a power regulator chip which supplies voltage to the gas and temp gauges.  Sometimes this chip gets bad contacts, sometimes it goes bad.  It is worth checking the ground wires to the transmission and to the back of the engine.  Don't ask me why Audi uses different grounds for the gauges...  But more than likely you will find a problem with the cluster itself.  Look for bad or corroded contacts, since both gauges stopped at the same time it will likely be on the ground side.  Good luck,  Jan