1999 Suburban headlight problem

Looking for some help with a problem on my 1999 suburban. I am having an intermittent problem with the headlights not turning on. One time they come on the next time they don't. All of the other systems appear to be functioning properly, ie. Daylight running lights are working and the brights will turn on when the normal headlights are not working. Any idea on what I could be wrong?
Thanks

relay or combo switch, most likely. Less likely, the daylight module.

Only way you're going to narrow it down is chase power when its not working.

Where would I locate the combo switch or the relay?
Thanks,
drsteve

the combo switch is the switch you turn on the headlights with.

The relay is usually in the engine compartment in a box with a bunch of other relays. Look up "relays" in your owners manual, it should tell you where they are and which is which.