One problem related to radio/tape cd player has been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
I've had problem with the electrical system. When I try to play the cd player it says check disc sometimes the disc will not eject from the radio. The clock always reset itself to incorrect time and not all lights stay lit on dash. Reported this incident twice to dealer they replaced sensor twice and here it is 2008 warranty has expired and still having same problems.