My 1995 Lumina LS 3.4L DOHC third brake light works, but not the main two. Everything else works fine.(turn signals and lights)

Most of the time the problem is in the turn signal switch. The third brake light circuit bypasses the turn signals.
Someone would need to check brake light power in and out of the turn signal switch.

sounds like you have a bad turn signal switch.

If the third brake light is working than we know the fuse is good and the switch is good. The third brake light bypasses the turn signal switch. If the rear turn signals are working than we also know that the wiring from the switch to the rear bulbs is also good. The brake lights and the turn signals are on the same bulb so the turn signal switch is what determines if the bulb gets power from the brake light switch or from the turn signal flasher. If the switch is bad usually the first thing that stops working is the brake lights.

Typically you can wiggle, jiggle, pull, push on the switch lever with you foot on the brake and get the brake lights to work. Sometimes turning the four way on and off several times will also get the brake lights to work. If this is the case than a new turn signal switch will solve you problem.

If you have any questions let me know!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

it could be the turn signal switch, voltage goes from the brake light switch to the turn signal then to the taillights, use a test light and follow the circuit from the pedat to the sockets, also check the grounds

In a Lumina if the brake lights quit working but the upper one in the rear window still works or your tun signals flash weakly or a different speeds the turn signal switch needs replaced. I will cure the problem. Not to hard a job, but does require removing the steering wheel and air bag assembly.

Check the bulbs everything runs as you said the 3rd brake light works correctly so should they all. Otherwise it may be the socket could be corroded check to ensure this is not your issue.

Will your Center High-Mount Stop Light (CHMSL) illuminate when you depress the brake pedal, but the lower/outer lights will not?
-- Do you have to hold the signal lever in a certain spot to get the turn signals to flash?
-- Do you have to hold the signal lever in a certain spot to get the lower/outer brake lights to illuminate?
-- Will the signals work in one direction, but not the other?
If you answered yes to any of the preceeding questions, your turn signal switch is likely malfunctioning.

**One more question before we continue: Is the turn signal lever not "cancelling" (returning to the "off" position) after you make a turn? If this is the case, you have a broken "cancelling spring."


Before you begin disassembly of your steering column, verify the turn signal flasher is not malfunctioning. If your brake lights work fine, but not the signals (either direction,) then it's likely the flasher is burnt out. The flasher itself is located underneath the dash near where the steering column passes through the firewall

Turn signal switch.

THE 3RD BRAKE LIGHT DOES NOT GO THROUGH THE TURN SIGNAL SWITCH.ASSUMING THE 3RD BRAKE LIGHT BULB IS GOOD.U SHOULD CHECK THE BRAKE LIGHT SWITCH ON THE BEAKE PEDAL.SHOULD BE POWER GOING IN & POWER OUT WHEN U ARE IN THE BRAKE

Blown parking lights fuse (check owners manual for location) If you have had an aftermarket radio recently installed, I suggest someone wired it wrong ...

First thing i would do is chg. the break light switch, and make sure to chk. all grounds around tailights, sometimes if there is a ground problem it will travel back thru the hot wire to get a ground, witch in turn makes everything go wackey.