Ok, I have a 2000 Tahoe Limited OBS with 5.7 (i put 99 to avoid the confusion between OBS and NBS). I've heard that the instruments are faulty from this period. One issue is my fuel guage. It reads accuratly but it vibrates extremly quickly. More urgent issue, the temp gauge shows that truck is hot. I've had truck tested with scan tool...def not overheating at all (188*190 F) However, the temp gauge shows 230-250 F. I've chaged both temp sensors and the thermostat....twice just to make sure. Anybody know if problem is in the inst cluster? Weird thing is, when engine is colder (in the morn) gauge shows 250+. After engine warms up, it comes back to around 230 F. Any help appreciated.

 

There have been a number of GM campaigns where they replaced the instrument cluster on many units. The symptoms were gauges showing very inaccurate results, jumping volt meter, fuel, temperature, etc. The steppers motors in the instrument cluster fail and unfortunately, cause the problem. It sounds like this could be your problem too. You may be able to get replacement steppers for your cluster and repair it yourself or get another cluster.

Good luck with your repair.