Unfortunately it's a PITA. There is a small access inside the trunk. You will see a small white connection which will "un-click" to be moved out of the way. from this access you will have to have the right angle to see the black socket. This requires actually getting in the trunk unless you are a Russian contortionist. the black socket rotates couterclock-wise. from here wressle the socket down being careful to not lose the bulb in the frame work of the trunk. Next replace and redo in reverse. This is a pretty frustrating process and I still have a burnt out bulb rolling around some where in the neather-area of my wifes trunk. All in all have some else do it next time you get the oil changed or tires replaced or just happen to be near the Hyundai service center. They may have a special tool or something that makes it easier. As for the other brake lights, piece of cake. It's just the third brake light that is a pain.
How to change third brake light in 2009 Hyundai sonata
In you trunk, pull back the padding behind the tail light, and repalce the according bulb.
remove the trunk lining or bend it back easy where the brake light is to access it and change it out.
Usually located at the bottom of the emergency brake handle - may have to remove trim for access
The fuel filter is in a difficult place to access. Look down under the brake master cylinder, up against the firewall.
i have an 03 sonata v6 base model... maybe the GLS does but the base doesn't.... i just rely on the squeelers on the brake pads..
The brake lights are accessed through the rear hatch. Find the panel on the rear sides of the car. Pop out the panel and access the brake lights. Replace the bulbs.
On my 2007 Sonata I had to replace the brake pads and rotors at 57000 miles.
From inside the trunk.
Should have an access panel inside trunk
You can gain access to the bulb from the trunk?
The brake light bald can be accessed through the trunk of the car. Remove the rear tail light cover to access the brake light bulb.