The rear light bulbs in a Lexus need to be checked and replaced every six months. Obviously, if they're not blown, you won't need to replace them. However, even though they are low-wattage bulbs, it's not uncommon for them to burn out twice a year. When they do go out, you can get replacement bulbs from just about any auto parts store---or from a Lexus or Toyota dealer, since Toyota owns Lexus. The part number you'll need will be on the bottom of the old bulb.
Open the trunk or hatch area. Pull up the rear cargo carpet and remove the wing nuts holding the rear trim piece to the tail light housing. Your Lexus may use bolts to hold the rear trim piece into place; the fastener type will depend on the year of your vehicle.
Pull off the rear trim.
Unplug the electrical connector from the rear bulb ballast. Push down on the top of the release tab on the connector, and pull it out of the ballast.
Turn the bulb counterclockwise to unlock it.
Pull the bulb out of the housing and insert a new bulb. Turn it clockwise to lock it.
Reconnect the electrical plug, replace the trim and fold the carpet back into place.
