2001 Jeep Grand Cherokee • 200,000 miles

When I turn on my headlights the tuning lights and fog lights come on but my low beam lights do not for like 20 min after high beam work what could be the problem I know a lot about vehicles but don't understand why my headlights will come on after 20 min I know it's not a fuse just would like to know how to fix it because I don't have time to bring it in do to work please help
October 17, 2013.

Check low beam relay and fuses in junction block lh side of dash

Oct 17, 2013.