06 Tahoe
#2
CF Monarch
Are the other gauges still working correctly? From 2003 to 2006 GM had a problem with the stepper motors used in their gauges. They will usually give faulty readings or could stop working completely. This may be your problem or it could also be the sending unit for the speedometer. If you do change the stepper, you should change all 6. They will all eventually go bad.