I recently experience the same problem with my 99 gs 300. my tail light on both sides are lit, my high beam lamp was burn out but did not solve the issue after i replace it. I had my 8yr son press the brake while i watch & notice that one of my high brake light was out. the high brake lamp has (5) small bulb & one was blown which cause the warning light to keep coming on. Like another person said, if your warning light is on, you have a blown/loose bulb somewhere. Pay close attention, Best result at night.