For your VF0's lighting issue, check the wiring for breaks or corrosion and inspect the fuse box for blown fuses. This could be why your voltmeter isn't picking up any voltage. When switching to an LED light, ensure compatibility with your vehicle's electrical system. You might need a resistor for proper functioning. At least, that's what I think from my experience, but every time I have any issue with the lightning, I check this website: https://leds.to/; they have articles on different topics and even some product suggestions so that it could be a helpful resource.