Gather your materials. You will need a replacement bulb and a screwdriver.
Open the rear liftgate of your 4Runner.
Locate the third brake light at the top center of the liftgate.
Remove the two screws holding the brake light assembly in place.
Gently pull the brake light assembly out of the liftgate.
Replace the old bulb with the new bulb.
Reinsert the brake light assembly into the liftgate and replace the screws.
Test the new bulb by pressing the brake pedal.