Sounds like we have the same problem. I recently purchased a 1998 ES300. Whenever the lights are turned on, the rear light warning light comes on. I checked all my rear lights; both tail lights, both turn signals, and both brake lights. Are there any other lights which are tied into the system? I could only find one light for each of the side of the car for the lights I mentioned above. Would the back-up lights or license plate lights be tied in to the warning indicator?