tail lights wont burn

My girl's dad has a 97 4wd hardbody and he called me last night saying the tail lights and tag lights wont burn. All front lamps work, the brake lights and signals still work in the rear when activated but the tails and tag lamps will not. He says he has power to the sockets and all the fuses he checked were ok. Any help would be super because I have no idea what to look for. thanks.

Have you checked for electrical continuity at the plug end?

No I havent been there yet, gonna look at it when i get off work. Was hopin to get a few ideas on what to check. Thanks

i would check for power on the bulb side of the socket if it has power there then it needs some bulbs

make sure the bulbs are making a connection to the socket too, ive had loose bulbs that did that

i would check the ground.

The Blinker/Headlamp switch sometimes goes bad and will lose the running lights.