Fule gauge speedometer and rpm gauges stopped

If all the gauges on your 2008 Chevy Tahoe have stopped working, it is possible that there may be an issue with the instrument cluster itself. A malfunctioning instrument cluster can cause the gauges to stop working all at once. Other potential causes could be faulty wiring, a blown fuse, or a defective sensor. I would recommend taking your vehicle to a qualified mechanic or dealership to have it diagnosed and repaired.

Is the air bag light lit on the instrument cluster ? If it is and the horn isn't working , probably because of a bad clock spring . Do you know what that is ?
How Clockspring Works

GM has problems ,2003 to 2006 . You may need yours repaired .

How to repair GM Instrument Cluster Speedometer Gauge Stepper

If the air bag light isn't lit , could be horn relay is bad ,

VEHICLE RELAYS Operation Diagnosis

You can if you know how to remove fuel tank ...the float is in the tank

please keep me posted as well, ALL my gauges are doing the same. First the gas, filled it one day and it fell all the way and light turned on, then my themostat, freaked me out, thought i was overheating,...NO just the guage, NOW my spedometer is stuck on 120, and my RPM's are acting crazy. i have read tons with this same problem, WHY WONT the manufacturer DO SOMTHING??

It sounds like your fule pump is going out, this would explain the no gas on your gauge. You need to replace the fule pump assembly, this will come with a new fule level sensor as well. Hope this helped, if you need some tips on removing the fule pump just let me know.

try to change the speed sensor

check all grounds

sounds like a fuse

Have the computer checked

On the 03-05 Cavalier instrument clusters this is a common problem, it's caused by failing stepper motors on the cluster's circuit board. It can be repaired though, check out this site for more on how to get it fixed - Cavalier instrument cluster repair