Im writing this in case anyone runs into the same issue i was having.

Since i bought my blazer ive had issues with my low beam headlights working about 90% of the time but randomly cutting out. The high-beams work fine and the parking lights and turn signals work fine. It was isolated to both of the low beams. I checked all of the normal stuff fuses, relays, headlamp switch, multi function switch. All of those were working properly. I even traced every ground i could find to make sure they were good. When i turned the headlamp switch on i could even feel the low beam relay clicking so i figured the switch and power wires were good.

In a last ditch effort before tracing individual wires I just turned the low beams on and started wiggling different wire harnesses around. when i moved the rear harness on the under hood fuse block my low beam suddenly came on. Then i wiggled it again and they turned off. Viola i finally found the source.
I unbolted the fuse block and removed the big rear plug. Then i removed the plastic cover to expose all of the pins. Pin #5 was pulled slightly out of the plug and a little crispy. So i repaired the pin and soldered the wire to ensure good contact. When i reinstalled everything my low beams came right on and worked just like they should.

I just hope this can help save someone else from chasing their tail in the future.

 

Good job on finding the fault and thanks for posting for others!

 

This has been haunting me for over a decade... hopefully your fix is the ticket! Thank you!

 

Thank YOU!!! I have a 2000 ZR2 Blazer, had the same thing and was the same issue.