99 burb drl problem

My 99, suburban 85+k miles, appears to have a drl problem. It started out as an occasional buzzing type noise when the headlights were engaged. When the buzzing noise is heard, the headlights flicker as does the drl light on the dash. The quick fix for this was to engage the hi beams and eventually the headlights would come on and all was well. However, now, I only have drls..no headlights or hi beams..the buzzing noise comes from under the dash to the left of the steering wheel...any thoughts???

Best guess is the DRL relay located in the convenience center (inside firewall near parking brake). Relay is bottom center position.

I read your post again and forget the DRL relay. It only controlls power to the low beams. I'm more inclined to suspect the DRL Module which is located under the dash left of the steering column. Could also be the headlight switch or the dimmer switch. Also check the "lighting" fuse in the underhood fuse block. Fuse #8//50amp. Sorry about the 1st post. I read yours too quick...........Steve

can I get the diode or switches at an auto parts store? I already checked the fuse and that was good and getting power. I will let you know how I make out (kids are home on break so time is limited :) Thanks again