It sounds to me like your bulbs are out. These bulbs have a lifespan just like the light bulbs in the lamps that you have at home. These are easy and cheap to replace, and you can usually access the bulbs from your trunk, if you own a car.
when my 1986 w-250 turn signal switch went out the brake lights quit working.
turn signal switch needs replaced!
Probably the flasher unit needs to be replaced. This is an electronic switch which usually mounts underneath the dashboard.
Assuming the signal lights still work, no. But a bad brake light switch or a blown brake light fuse could.
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.
It needs checked out but both the hazard and brake lights go through the turn signal switch.
If the turn signal is working it's either the brake light switch or the turn signal switch.
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.
Bad bulbs? Sockets corroded?
If the fuses and bulbs are okay I would blame the signal switch assembly. They call it a multi-function switch these days.
blubs blown? Check the turn signal switch.
the turn signal switch is probably bad