1993 silverado rear lights

I was driving home other night in the snow when all the rear lights in my 1993 chevy silverado just stopped working my father checked fuses and looked at wire couldn't see a reason why this would have happend. desprately need it fixed

if the tail light fuse is good check the brown wire out of the headlight switch. see if you have power on the brown wire when you have the parking lights on. Do you have a trailer connector on your vehicle? Easiest to check there. you should show ground with the light switch off and power when it is on. Parking lights are for the tail lights and front markers. Headlights are for the headlights only.