How do you change the third brake light

Check for Pinched wiring in rear door hatch.Wiring harness runs in door hatch & open/closing of door ALWAYS PINCHES HARNESS!!!!!!

If the bulbs are good, it could be the brake light switch, or the turn signal switch. The third brake light bypasses the turn signal switch.

check the light socket it could be lose on the wires or just the light

If you are referring to the Third Brake Light mounted at the top of the rear hatch, then there should be 2 screws on either side of the lense. Remove those two screws and pull the lense off. You can now twist the bulb socket counter-clockwise and remove it from the lense.

Above the third brake light is a small panel, remove this panel using small screwdriver.
1. You'll see four (4) bolts, remove the three bolts that are painted black, do not remove the center bolt holding the plastic molding, this is for the door molding, and has nothing to do with the light.
2. Once those three bolts are out, you'll see two more small screws, remove them and you'll have access to the third brake light bulb.

Be careful when pulling out the bulb, my bulb broke, and I'm still trying to get pieces out! - Good luck.

you have to remove the taillamp assembly. there should be 2 screws(possibly torx heads)on the side when you open the hatch,remove those screws and pull the taillight out-the just unscrew the bulb

same thing happened to us.  My wife came home and said the rear brake lights were stuck on so I assumed it was the brake switch...not so. Took car for a ride and noticed rear wiper did not work and when I hit the brake the rear hatched opened and door locks blew out.  I started by looking at the wires in the gromet above the hatch and found almost all the wires were bare.  Therefore power was jumping  the bare wires and traveling back down the third break light and to the rear brake lights and visa versa.. a very dangerous situation.  The best that I can tell is the wires are so short in length that they pull and chafe every time you open and close the hatch...very poor design...   Note: we bought our vehicle brand new and some of the wires had electrical tape on them....seems mickey moused.

Test the brake light switch by the brake pedal for electrical power and operation with a 12 V test light

Turn signal switch 95% of t he time. Try to work your hazards, if it stuck at all will also cause this.

Open the full hatch.
Pull down the weather strip near the rear dome light.
There should be a wire with a connector in it. Disconnect it
Close the full hatch.

Open just the window hatch. There is 1 screw on either side of the bulb housing.