I recently had to replace the trunk light in my '97 ES300.
If you just need the bulb, it's NOT replacement #194 that Walmart, Advanced Auto and others list.
You need a 12V, 3 Watt bulb that looks like a fuse. I finally had to buy mine from our local Lexus dealer.
Pop open the light cover with a screwdriver and carefully pull out the bulb.
Try this first because it's probably only the bulb that is bad.
Follow the link below, labeled "How to replace a Lexus IS300 tail light"
To change brake light bulbs on a 1998 Lexus ES300, open the trunk lid. Locate the plastic rivet on the side of the trunk liner. Turn the rivet while pushing in with a screwdriver. Remove the rivet and the trunk liner can be pulled away to access the bulb. Push in and turn the bulb to remove. Insert the new bulb the same way. Replace the rivet in the trunk liner.
The 3rd brake light can be replaced by removing the subwoofer cover by pushing down and towards the front of the car, other brake lights can be replaced by opening velcro covers on inside of trunk lid.
In the trunk
Along the rear of the inside of the trunk there are four small bolts which need to be removed. Once removed, you will be able to push out the outer plastic cover holdind the light bulbs and wiring. From there, you can easily remove and replace the bulbs.
The fuses are all mapped out on the inside of the fusebox cover
You can access the brake light bald through the trunk compartment. Remove the trunk liner from the tail light assembly. Push the brake light connector in and turn at the same time. The brake lightbulb will come out. Reverse the process to install the new brake light
if you open the trunk you will find a carpeted section on the lid and in the corner of the trunk where the lights are. You need to open the access doors to the light bulbs and replace the bulbs. the sensor will need to be reset by someone that can reset the codes
open trunk lid and locate the trunk light switch.push switch to see if light goes off. if light does not go off, replace switch. if light does go off, adjust switch to where trunk lid operates switch when trunk is closed
From inside the trunk.
From inside the trunk.
There are two screws outside the car (near the trunk) and one inside the trunk behind the light that need to be removed. Then slide off th whole panel and replace the bad light.