Two problems related to fog light switch have been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
The headlines turn off by themselves while I am driving at night. This problem has been going on since January of 2015. I have taken the vehicle to several shops, and even the dealer, but nobody knows how to fix the problem. Currently, the headlights only work in high beam. I drive with high beam lights and fog lights. Either way it is a safety issue. High beams can cause accidents. Driving with no lights can cause accidents. Lights shutting off while I am driving can cause accidents and/or death.
While going approximately 60 mph the low beam headlights just go out with only the parking lights and fog lights working. Also most of the gauges on the instrument panel do not work including the gas gauge. After some internet research many others are having these same issues.