Only middle brake light works

that leaves only 1 thing WIRE (and sub catagory connectors, same really)
use a walfar $10 volt meter, and stop guessing.
start any where you want, the lamps the middle or like me
the fuse.
12v both sides of the brake fuse? no? then you need to learn real fuse testing, use a voltmeter. it will never ever lie to you like eye balls on fuse can.

replace brake light switch @ BRAKE PEDAL, next, replace turnsignal flasher under dash, check for blown fuse, if turn sig. still doesn't work, check turnsig., switch, & or for loose connection.

check for power at the wires going intop the tail lights, real common that the circuit board is bad, but unlikely both at the same time. The tag, tail lights and brakes are 2 different systems. Do the turn signals work normally? if so the wiring from the turn signal switch to the brake lights is GOOD. the stop light switch had\s a ORANGE wire that should have 12V if not ck STOP LPS fuse, when brake pedal is depressed, the WHITE wire is 12V (at the stop light switch) if that is OK, the turn signal switch COULD be bad. The wiring harness plug is near the back left under the tailgate, see if that is disconnected?

The flasher does not stop the brake lights from working. Check # 18 fuse in fusebox under lower left side of dash. if it's ok, the brake light switch, on the brake pedal arm is next. light green wire with red stripe is hot if fuse 18 is ok. Depress brake pedal, light green with no stripe should have power. if not, replace brake light switch. If light green wire has power with pedal depressed, combination switch under the steering is next. Remove the cover from around the combo switch {under the steering wheel}. depress brake pedal, light green wire should have power. If it does, pedal still depressed, orange with light blue wire & wire with light green & orange should have power. Those 2 wires are brake & rear turn signal wires. { The turn signal switch should be in the middle, not right position or left. while checking for power in the last 2 wires. Good Luck drvolt.

WITH A GOOD FUSE TESTER, TEST ALL THE FUSES FUSEBOX UNDER THE HOOD & INSIDE THE VEHICLE. IF THE FUSES ARE ALL GOOD WITH THE TESTER YOU MUST HAVE A BAD BRAKE LIGHT SWITCH OR A BAD TURN SIGNAL SWITCH. THE BRAKE LIGHT CIRCUIT GOES UP THROUGH THE TURN SIGNAL SWITCH & THEN TO THE BRAKE LIGHTS. FIRST OF ALL IS THE BRAKE LIGHT SWITCH GOOD ? THE ORANGE WIRE FEEDS THE BRAKE LIGHT SWITCH, THE WHITE WIRE PUTS POWER TO THE TURN SIGNAL SWITCH, SO THE LIGHTS CAN BE USED AS TURN LIGHTS OR BRAKE LIGHTS. , PUT A TESTER IN THE WHITE WIRE & PRESS ON THE BRAKE PEDAL. IF THE TEST LIGHT LIGHTS UP, BRAKE LIGHT SWITCH IS GOOD, BY THE WAY THE BRAKE LIGHT FUSE MAY BE LABELED" STOP", THE FUSE LABELED" BRAKE" IS FOR THE ABS SYSTEM. TO CHECK THE TURN SIGNAL SWITCH FOR BRAKE LIGHTS, REMOVE THE PLASTIC COVER FROM UNDER THE STEERING WHEEL, PRESS ON THE BRAKE PEDAL, PUT THE TESTER IN THE SMALL YELLOW WIRE, THEN THE SMALL GREEN WIRE. IF THERE IS NO POWER IN EITHER WIRE, THE TURN SIGNAL SWITCH IS BAD.

Very popular problem for this vehicle. Check for power at the brakelight switch. If you have power, depress the pedal and make sure the power is transfered to the next terminal. The switch is very affordabl and quite simple to exchange. Good luck, Dana

Check your fuses of course,you probably did.Listen your not going to believe this,the wire at the brake light switch can be bad.sometines the wire can break inside the vinyl cover just a milameter.use a test light for presence of voltage at the switch and check a few inches back to see it voltage is present. MAKE SURE YOU HAVE VOLTAGE AT THE SWITCH!

check the brake switch and wires sometimes the wire break at the connector

ljones, Did you check the "VEH stop" fuse in the left side instrument panel fuse box. There are 3 stop light fuses, 1 for all the stop lights located in the under hood fuse box. 2 in the left side IP fuse box. 1 for the upper stop light and 1 for the lower stop lights. The fuse box in the IP is where the upper and lower stop lights split. Let me know.

I have the same problem,it's the switch inside the turn signal assembly.Unfortunately the entire assembly switch and all has to be replaced.
Hope this helps.