My speedometer stays on 10 mph. Where should I start.

Customer Concern: The speedometer is inoperative. Other gauges OK. Tests/Procedures: 1. Check that the odometer works. 2. If so, send the Instrument Panel Cluster (IPC) in for repair or replace the IPC. 3. NOTE: A new IPC must be programmed. 4. If the odometer is inoperative also, check IPC data for MPH. Potential Causes: Instrument Panel Cluster (IPC)

This is very common on the 03-06 Silverados. The cause is the motors behind the gauges are failing, they all go out eventually. You can get it repaired here - www.drspeedometer.com and there's a DIY guide here - www.howtorepairmyinstrumentcluster.com