This is what I have so far:

1. Replaced both bulbs
2. Checked HDLP relay , clicks when you turn on lights
3. Checked voltage at HDLP fuses, both at 12volts when relay is engaged , continuity’s are good

This seems to indicate that there is a failure between the fuse and the bulb, or a failure between the bulb and the ground. Both circuits are independent ,and have no active components down stream of the fuses. I lost one low beam, then shortly lost the other, so in a rush, I replaced the bulbs, and did not trouble shoot at the low beams, big mistake, it’s not easy to change the bulb, you have to pull the head lights. I saw the high beams , mistook them for the low beams. With all that said , I still need to pull the lights and determine if the failure is the power or ground. It Just amazes me that two independent circuits would go out together in a short period of time.

Another interesting fact is that when you turn on the high beams, you don’t lose power at the low beam fuses, I thought BCM was supposed to cut the low beams off, when the highs were turned on?

I have a 2008 suburban

Any help is appreciated thanks

 

solved the problem, new spyder head lights low beam plug did not exactly line up with the original light harness, and the plug prongs were bent in both fixtures. I spread the prongs a little and carefully inserted them, all is good.