01 Deville instrument cluster, HVAC display dark
 

I have searched and searched for help on this problem. 2001 Cadillac Deville

About a year ago, my instrument cluster and HVAC controls went dark. About a day later they were back on and never turned off again...until last Friday. This time they did not come back on. I was turning the ignition on/off a few times to check a brake fluid sensor warning message (to see if I corrected the problem replacing the sensor on the brake reservoir that was giving me problems) and suddenly the Attempted Theft warning came on the dash. Then everything went dark. I have checked all fuses, and swapped some relays in both fuse boxes to see if I could find the problem. No such luck. Today my digital dash is dark and HVAC is also dark yet everything is working fine. I went to a dealership and they thought it may be the ignition module and stated that they would recommend replacing that first so they have a place to start troubleshooting from. I do not think it is the ignition module but I ordered a new one which will be here in a few days. This absolutely baffles me since everything was working fine prior and all digital gauges on both displays were working fine prior to Friday. I have been reading lots and lots of posts on individuals who had similar type issues. No solutions. I have also done the battery disconnect/hard reset touch red and black together to drain computers. etc. for several minutes also...didn't work. Need help solving this one please.

Well today I was driving and all of a sudden everything just popped back on. Full instrumentation and HVAC back. Don't know how long it will work, but it's back for now. Ignition Module still coming this week so we will replace when it arrives but if it stays working there will be no way to verify it is a fix or not. But clearly we know its not a fuse. Any input would be appreciated.

Installed new Ignition Module today, running good, but then it fixed itself a few days ago so cannot tell if this fixed it or not. Time will tell.

Does it still work? My 2004 HVAC display goes on and off daily. I never know when it might work and when it might just go black for a few days.