One problem related to brake light on has been reported for the 2000 Lexus GS300. The most recently reported issues are listed below.
Regarding my 2000 GS 300 Lexus. Brake, abs, vsc, vsc off lights along with loud alarm displayed. Also has had an annoying on and off chirping noise before this alarm sounded. The breaks appear to be working without any problems. The chirping noise is heard on the drivers side and doesn't seem to matter whether car is moving or driving and sometimes is not heard at all and the car drives fine without any mechanical problems. But when the brake light came on it was accompanied with a shrill alarm that sounded for about 10 minutes and went off. I took the vehicle to my mechanic and he said it was the hydraulic brake pump and would cost $3700 to fix. This is a lot of money and I am afraid the brakes will go out and afraid to drive it since my brakes may suddenly go out.