Yes, they did.
If the headlights on the 2004 GMC Envoy are not working, there could be a loose connection somewhere. If all of the other lights are working, it is most likely not a fuse that has blown. Double check the wiring to see if there is a loose connection.
Check the bulbs and check the fuses.
answer: replace the headlights switch.
There are individuak fuses for each headlight
Make sure fuse is installed and not loose - same fuse controls parking/tail and dash lights
You must have two headlights, all other lights are in fact not headlights and just additional light aids.
Check bulbs & fuses first. If still a problem you will need to start looking at possible wiring issues
Check to see if the dash lights dim or if the tail lights come on when the light switch is turned on. If these other lights work then check for a headlight relay. Most likely causes are either the switch or the relay.
The required height of headlights, tail lights, and other auxiliary lights varies from state to state. StreetLegalLaws.com has a current list of lighting equipment laws for each state.
On my 98 sunfire, the tail lights and marker lights only work if you turn on the headlights. If only the daytime lights are on, the Pontiac on the trunk is illuminated but no other lights at the rear until brakes or turn signals are activated. This is common with a lot of vehicles out there. Daytime running lights are not necessarily the same candle power as the headlights. I can tell a big difference in mine.
Sounds like the switch is bad. You can buy a replacement switch at any automotive parts store and they are not that hard to install. Also check the fuse as sometimes the headlights have their own fuse while the parking/brake/back-up lights have their own.
I just had the same problem in my '97 Nissan pickup. Both headlights stopped working at the same time. I went through some hoops, including trying a new headlight switch, but it turned out to be some corrosion in the plug for the fusible link that bolts onto the positive terminal of the battery. I cleaned that out and it is working fine again.