The 2006 Hyundai Sonata has a third brake light. This light is mounted in the partition between the rear seats and the rear glass. The third brake light is referred to as a high-mount stop light. If you notice the third brake light is not working, the likely culprit is a faulty bulb. Replace the bulb to restore the light to working condition.
Turn the Sonata's engine off. Open the car's hood. Loosen the nut around the negative battery cable. Pull the cable upward to separate it from the battery.
Open the trunk. Look in the rear part of the trunk beneath the third brake light. You will see a wiring harness. Unplug the wiring harness.
Remove the two Phillips screws above the wiring harness. These screws secure the third brake light package tray, which is mounted in the rear seating area.
Access the rear seating area. Find the third brake light package tray in the partition between the rear seat and the rear glass. Lift it upward to remove it. With the screws out, it comes up easily.
Pull the bulb straight out of its socket. Insert the new bulb into the socket. Replace the third brake light package tray. Move back to the trunk.
Insert the package tray screws and tighten them. Reconnect the wiring harness. Close the trunk.
Place the negative battery cable back onto the battery post. Tighten the nut around the cable to reconnect the battery. Close the hood.
