My name is XXXXX XXXXX X am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.
From what you have described here this sounds like either low voltage or a poor ground signal to the low beams.
Your low beam bulbs should have two wires attached to the socket for the bulb.Make sure the wires and sockets are not corroded.If this is o.k. next would be to test the two wires with a multi meter.One wire should have battery voltage when the lights are switched on and one should have a ground signal.
If one of these signals are missing or low on voltage then the wiring would need checked to see if the ground connection is poor or corroded or if the voltage signal is corroded or damaged as well.
If these are o.k. then further testing would need done to see if this is the headlight switch itself at fault possibly or another component like a low beam relay.
I hope this info has helped here and if you need anything else let me know.