What causes the low beam lights not to come on but the high beams come on.

Checked fuses they are good

DRL'S working?

I have this same issue - DRLs/Low-beam are not working yet the high beams etc all work. Replaced the 15V fuses for both headlights with known good fuses and the issue persists. I suppose it's possible the bulbs need to be replaced, but I'm concerned about damaging some of the cheap plastic bits that GM used to attach the grille. Any other thoughts? A $50 solution seems like a better choice than taking my vehicle in to GM and paying ~$300.