When you say it's not working, do you mean it's dead and pegged at zero, or it's not accurate, or it fluctuates?
I've read quite a few posts on various GM truck forums about this issue, most ended up with replaced instrument clusters from the dealer. If you are under warranty bring it back if not there is a guy on ebay who rebuilds instrument clusters with a quick turnaround here is his name and email address.chevydude said:2004 silverado....speedometer isnt working....is this happening on any other newer chevy pickups out there.?