REAR turn signals and brake lights not working

I have a 97 Sonoma, and the rear turn signals and the brake lights don't work. I tried switching the bulbs. Still nothing. The side lights and reverse lights work. But when I try to signal, turn on my hazards, or brake, I'm not getting anything. I did check the fuses under the dash, and they all seem to be ok. Any suggestions?

Follow the wires under the body. There are 2 plugs that might have come apart.

A good old fashion bulb type test light is your best buddie on them kind of problems.

Check for 12 volts to tail lights and do not forget grounds.

Another problem area to check is a spliced in trailer plug set up.
The splice in will give you corroded/green wiring.

I looked underneath, and didn't see any wires disconnected. I was just wondering if there might be a switch or relay that both the back brake lights and turn signals work. Everything works fine up front. When my headlights are on, the lamps are on in the back, and both of my reverse lights work. It's just the brake and rear turn signals. I'm totally illiterate when it comes to vehicles. I just might have to take it in. But it just seems like something simple, since those are the only things not working. But I guess with electrical, 99% of problems aren't just simple.

Do you have a test light?
Does the truck have a trailer plug on it.
Brake light and turn signals use the same wire.
With turn signal on and flashing check for 12 volts to rear turn signal bulb.
One side should be yellow and other side green wire.
MT