I pretty sure I have figured out the issue but would like to see what you all think. This is on a 77 Chevy Silverado C10. The light sockets are metal and "snap" into the bumper holes. Here's the type of lights I'm talking about, mine are just rusted everywhere. So the lights are not coming on, got new bulbs, nothing, then got the meter out. I have power all the way to the ends only if I ground the meter to the bumper or other metals. When I try and ground the meter to the bulb housing, nothing. The bulb housings were covered in rust, sanded, cleaned them. Now I get a small reading with the meter but not enough for the lights to come on. I don't think there getting a good ground anymore, time for some new bulb housings?