99' Tahoe buzzing electrical problem

I have a 99' Chev. Tahoe. I noticed one evening when I pulled into the garage that the "high beam" light was on but the hi beam head lights were not. When I did click the high beams on, then the "high beam" indicator light lit up much brighter. Then the next day I checked this again and yes the high beam indicator light was still on even though the head lights were off. I then pulled on the blinker lever as if to turn the high beam lights on (even though the head lights were not turned on at this point) and could hear a buzzing. There seems to be a little relay switch that is just buzzing away under the dash by the brake pedal when the blinker lever is in the high beam position with the lights off. If the head lights are actually turned on you do not hear this relay buzzing and the head lights work fine (except that the high beam light is on (dimly) when the head lights are in the low beam setting). I found one of the drivers side rear blinker lights out and changed it thinking this buzzing problem would go away but it hasn't. All the other lights appear to be working properly. Any ideas anyone?

Check the diode for the DRL system (usually located in the underhood fuse/relay panel).