The bulbs used for the Kia Optima's brake lights are low wattage and usually last a long time. But you should check your bulbs every six months at least to ensure they are working properly. Condensation can form on the interior of the bulb housing, and that can be enough to make them fail. When replacing the bulbs, make sure you have the correct part number, which is located on the base of the old bulb.
Open the hood and locate the battery. Remove the cable from the negative terminal (black cable) by turning the retaining nut on the cable clamp counterclockwise with a socket wrench until the clamp is loose enough to slide off the terminal. You must disconnect the battery's negative terminal to avoid a potential electrical shock when working on any electrical component in your KIA.
Open the trunk and pull back the carpet near the tail light assembly.
Remove the three nuts holding the lamp assembly in place and pull the lamp assembly out.
Remove the bulb assembly by rotating the bulb counterclockwise and pulling the bulb straight out of the housing.
Install the new bulb. Installation is the reverse of removal.
Reconnect the cable to the negative battery terminal.
