Two problems related to headlight switch have been reported for the 2004 GMC Envoy. The most recently reported issues are listed below.
While driving at night both low beam headlights go out completely without warning. Vehicle traveling at highway speed and has happened while driving in city as well. Highbeam headlights work when switched on after low beam stop working. Cannot leagally drive with highbeams on always. My Envoy is in excellent condition and is dealer serviced even though it has high mileage. There was a recall for 2006 and up for this type issue, why was the 2004 model year not looked at? there are others that have had the same issue with lowbeam headlights. Fusebox underhood is labeled to confuse owner and relays not described well in owners manual. There is no relay listed for low beam headlights. Headlight driver module is a know failure component. Gm also changed onstar to digital system leaving gm cars like mine with analog onstar unservicable and requires expensive upgrade. Headlights going dark while driving at night is a danger and vehicle should be required to fall under recall for 2006 models as well. Slight accident, ran off road into ditch and caused light damage. Vehicle was able to be driven, but needed some repair.
My dash panel gauges began failing one by one. My headlights will sometimes not come on after starting the car with the headlight switch on auto. A flick of the headlight switch in and off, does not make the headlights come on. Sometimes they come on after driving around, and then will go off without touching the switch. Now, my side brakelights will not operate correctly when the brake pedal is pressed. Only the third brake light illuminates.