The daytime headlights and the low beam headlights will not come on. I have checked all low beam and daylight running light fuses and relays in the under hood fuse box, and they are ok.
Low beam headlights won't come on. on 2004 GMC Yukon Denali
Do your brights work? If they do then it is most likely a switch or light module problem. here is a link to an online repair manual site, that will have the wring diagrams to use to inspect your problem.