How Instrument Clusters Work & What to do When Gauges Go Bad.
MotorWeek's Pat Goss (RockAuto.com is a MotorWeek Sponsor) demonstrates how modern instrument clusters work and explains what can make gauges go bad. He shows replacement instrument clusters by Dorman (found under "Body-Interior" at RockAuto.com) that are relatively inexpensive and often better made than the original gauge cluster.
Instrument Panel Cluster Malfunction
As you can see my 2004 GMC truck speedometer has malfunction. The dealer said it will cost between $400 and $600 dollars to replace. I look on the internet and found a special bulletin from GMC. I called GMC and they said it will only cost $120 for the labor to replace. The special bulletin will cover the part cost. I hope this can help you. Go to http://www.gm-trucks.com/forums/index.php?showtopic=70134
How To Disassemble A Chevrolet Gauge Cluster & Stepper Motor Removal
Video of me taking apart a Chevy Silverado instrument panel. This is also the procedure for stepper motor replacement if you have a guage that isn't working correctly. The disassembly process is the same for many GM vehicles.