More than likely if the brake lights and the turnsignals don't work, You need a new turn signal indicator switch located behind steering wheel in column. Usually have to take it to a shop because it requires a special tool to get column apart.
the turn signal switch is probably bad
Fuse
If you have the same bulb for brake and signal, brake light power needs to be interrupted by the signal lights, The brake circuit has to go through the signal light switch so the problem could be there.
Since most brake/turn use the same filament in the bulb(1157) then if the turn signal switch is bad or offset then it will effect the brake lights.
Check and make sure you have the correct bulb. The turn signal/brake light is a dual element bulb and if you have a single element it does not work properly.
Tail lights. Brake lights. Backup lights. Signal lights. License plate lights.
I would check the running lights for one with a short. I had the same sort of thing with my trailer and I spent way to much time troubleshooting the brake and signal wires. Turns out a running light bulb connector was grounding out on the trailer and messing it all up.
either dimmer switch or blown fuse If you are saying that the tail brake lights are working but the third brake light is not....It may be a defective turn signal switch in the steering column.
Blinkers can work without brake lights. Brake lights are activated by a switch that is switched by the brake petal and the turn signals are acivated by your turn signal switch on your steering column. The two are two separate circuits. I suggest you check out the switch on your brake pedal to see if it is working properly. It must have 12 volts applied to one side when it is not acitvated and 12 volts should be on both sides when it is activated. When the 12 volts is on both sides of the brake switch, it should apply 12 volts to your brake lights and then they should come on.
Assuming the signal lights still work, no. But a bad brake light switch or a blown brake light fuse could.
One of two things. Either the brake light switch behind the brake pedal. Or try wiggling or rotating your turn signal stalk in a circle motion. If the brake lights work when the turn signal stalk is wiggled then you need to replace the turn signal stalk.
Check the brake light fuse, the bulbs, the brake light switch and last, check the signal switch.