I have a 2008 Z71 Tahoe. The other day both of my low beam headlamps stopped working. The parking lights, brights and running lights still work. I changed the bulbs, checked fuses and checked relays with no change. When I turn the knob inside I can hear it clicking in the fuse box for each setting, but cannot get the lights to work. Does anyone have any ideas or have you dealt with this before?! This is driving me crazy!