Ok, so I have a 2000 Sierra, 5.3 auto, SLE. My DRL's used to work no problem. Then, some time ago, they decided to stop working. Symptoms: DRLs do not turn on (the little light next to the turn signal) Low beam headlights come on and stay on as if the DRLs were working properly and it was dark. Dash lights also act as if the DRLs were working and it was just dark. Trouble shooting attempts: I've looked at all the fuses and Relays and they are all working correctly and aren't blown. Changed the ambient light sensor with two other ones that I got out of a junk yard. The DRL light bulbs aren't burnt out. Looked over some of the wires and couldn't find any broken, frayed, or unplugged wires. Searched the internet for any possible answers, procedures, and fixes and found none. I'm thinking that putting a small LED into the ambient light sensor will give the system the resistance that it needs to think that it is daylight. This will result in the DRL's coming on, but me having to manually turn on the head lights, which I'm ok with. Any thoughts, comments, experiences?