I have a 2008 Hyundai Accent and none of my brake lights work. I tried replacing the bulbs with no luck.

Hello Tom,

I had a similar trouble in an '86 BMW ... I was able to
find simply by touching it. Of course I returned...I ultimately found water intrusion, fixed the gasket, cleaned the contact and prevented further corrosion wit WHITE LITHIUM grease.
We all lived happily ever after...

I would have found it sooner if I had pulled out both back lights and simply swapped them... because the corrosion was INSIDE the (twist-out) light socket. I'm suggesting you have a weak (high resistance) ground... either at your light socket or possibly inside your bulb.

If what I am thinking is correct... You "combo" bulb should be on... When the flasher is activated... The BRIGHTER element should ALSO light... Brighter...
With a poor ground... both elements would OVER-POWER
the ground and the light would appear to flash on & OFF...
Rather than Bright & brighter.

Change the bulb, clean correct the socket... Inspect the GROUND

'08 Accent Technical Service Bulletins and wiring diagrams are available at an excellent site: BBB INDUSTRIES web site
(see below: registration is required for EULA purposes))...
FREE.

"TSB 15-BE-004" (hold this thought for later)

Your car show a TECHNICAL SERVICE BULLETIN that
indicates chronic connector issues... so it is not unlikely
this could be a possible connector issue...
(bulletin indicates there are "kits" for your various connectors).


Right now ...
I saw a YOU HAD a past issue with your brake lights which adds a possible level of complexity... How that was resolved...?

The CIRCUIT DRAWINGS indicate you have "combo" (dual element) bulbs at all four corners of your car... for the sake of simplicity I'm going to assume dual element 1157/2357 type
(amber in the front, clear at rear...
(Although ROCK-AUTO shows LED (as possible))...

Comment me back if you move the bulbs and nothing changes... we'll have to MEASURE the ground circuit & check for
"connector issues"

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More Information for GE 2357NA

2008 HYUNDAI ACCENT 1 6L L4 Turn Signal Lamp Bulb RockAuto

Check your brake light switch on the brake pedal. See if it has power. Check one side for poer and the other for power while applying the brakes. If it has power its most likely the turn signal switch Brake lights also go thru that switch.