Brake light and rear blinker issue

I have a 87 Chevy c10 and I am now trying to get the lights to work right the front lights all work perfectly and the taillights also work but the brake lights don't neither do the rear blinkers work at all any ideas?

Bad ground somewhere maybe? Did u try changing the bulbs? I doubt both bulbs blew that filament at once, but stranger things have happened

Try pushing and pulling the hazard switch a couple times. Make sure you have power on the orange wire at the brake switch, and power on the white wire when you press the brake pedal. If that checks out, check for power on the yellow and green wires (at the turn signal switch) with the brake pedal pressed. If that’s ok, release the brake pedal turn the key to run, and move the turn signal lever. You should have power on the green and yellow wires depending on which position the turn signal is in. If all that check out, your problem is downstream of the steering column. Start inspecting wires and sockets.

I assume you checked the bulbs first?

Thanks guys. Most of the bulbs are new

There is a rear harness ground up under the back bumper, about in the middle of the truck. It might be corroded or have broken off. On my truck its a fairly large gauge (12?) white wire.

There is also a big plug under the back bumper and you can unplug it and add a T-connector for trailer lights (most trailer shops sell them). You could add one for trailer lights, which would give you a test point to make sure all the connections are working. If anything does not work at that point (which is before the taillights) you need to trace the wires back along the frame rail and up to the engine compartment. The wiring is easy to see and trace from under the truck.
This is one of the T-one connectors from Curt, but Reese and others sell the same item.
https://www.curtmfg.com/part/55311

Bruce

I think all lights (running turns and brakes use the same ground)

brake and turn signals use same filament in bulb, running lights use the other filament (double filament bulb) think 1056 and 1057 bulbs
so basically turn signals flash the brake lights if all turn and brake lights are out you may have problem before the rear plug

I would start a brake pedal switch ( easy check 2 wires for voltage in and out) if good
lots of pinout sheets on the rear plug I would check for voltage on right and left brake wires (make sure brake is applied)

I had same problem on 77, turned out to be turn signal switch in steering column