One problem related to dash wiring has been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
The blower motor on our 2004 GMC Envoy quit working and upon taking it to the dealer to repair, the dealer indicated that the blower motor resistor and the wiring harness that plugs into the resistor had melted together. When attempting to order the two parts (resistor and wiring harness), it was determined that the wiring harness is on nationwide backorder. The service manager also indicated that he has 5 others on backorder. From that comment, he indicated that there is a major issue with the wiring harness and resistor melting together on a national basis. The fact that the heat was so great to melt these two components together clearly indicates a possible fire and safety hazard. I believe it's something that should be investigated and a recall issued.