Gauge cluster failures
 

So I am on my third gauge cluster as of last night. The previous two both failed in the same way. All of the warning lights continue to work. The odometer continues to work also but all of the analog gauges and the digital readout for the speedo and clock die completely. The back lighting with headlights on also dies. I have looked every where for loose grounds on the strip behind the cluster and at every wire loom I can see and there are no visual issues. I have also checked all of the fuses with a test light and they are good.
Any ideas? It's getting expensive even buying used clusters.
Thanks guys!

I do repairs of 986/996 instrument clusters as well as automotive electronics in general, specializing in European brands, for people all over. One was recently sent to Dubai, and another to Switzerland. I have repaired a bunch of late 986/996 clusters and a few of the early ones, including a late 996 Cup cluster ('05, but it uses the early cluster - a real oddball) that had a problem which sounded like what you are experiencing. Most of what I see is problems with the oil level measurement circuitry, but I have done a few others as well. If you would like, I could have a look at one of your clusters and see if I can figure out what is killing them for you.

That would be great. Where do I send it? How much for the diagnostic? PM me if you want. Thanks!

The blue/gray wire on the blue connector on the gauge goes to many places in the center console to light up the backlight for the climate control unit, the radio, buttons, ash tray compartment, etc. Check to make sure that is not shorted to ground somewhere back there.

I had a problem with my gauge cluster backlight not working and it was because the blue/gray wire was shorted to ground behind the radio. The gauge backlight connects directly to the blue/gray wire.

I highly recommend getting a wiring diagram from the Bentley manual and following all the wires through.

First off, try cycling the connectors that go between the front and back of the cluster. I don't have one of those clusters here right now, but there are two connectors that slide to disconnect the front part with the gauges and knobs from the rear half with the circuit board. This is how you access the bulbs for the gauges. Sometimes you can have a bad connection there, especially on the ground connections. I am sure there is a link somewhere here to how to get at the bulbs...

I will send you a PM as well.