2003 Silverado no tail lights
 

Randomly the tail lights quit working. Or also called running lights. The brake lights and turn signals work. License plate lights dont. But I believe they run off the same fuse. I started out checking the lr and rr park fuses. They were good. Bulbs are brand new. Tried switching relays around, that didn't work. Put in a brand new headlight switch. Didn't work either. Checked for power to both of the fuses and got nothing. Also tried taking a wire and applying direct power to the fuses. And they did not turn on. So could someone send me in the correct direction on where to look next? Maybe a bad ground, broken wire, or bad fuse block? Both sides went out at the same time though. Any help is appreciated

it does sound like a bad ground. there should be a ground near the back side of the truck that all of the lights ground to. cant remember the details as it has been several years since i played around with that ground.

i would say, with the lights on, or should be on, take a test light and test the bulb terminals in the socket to a known good ground. if you are getting power to the socket then you know it is a ground issue. if there is no power then it is a supply issue.