Two problems related to dash wiring have been reported for the 2004 GMC Sierra. The most recently reported issues are listed below.
Speedometer and gauge cluster have worked intermittently for the past few weeks and have now completely failed. I have talked to several other gm truck owners and apparently this an extremely common occurrence. Some of them were lucky enough to have gotten it covered. I see from the complaint search that there are a number of complaints here as well. Gm charges an outrageous amount to fix this issue as it requires complete replacement of the cluster. If a total failure of a cluster including the speedometer isn't a safety hazard, I don't know what is.
Speedometer is stuck at 65 mph & goes up from there so it is impossible to know how fast the vehicle is moving. This is very dangerous. I called GMC about recalls & they said there are none.