shadak

i've lost my owners manual, and have had a warning light intemittently on for the past few weeks now, i would appreciate someone telling me what the warning means. it looks like this (O) with ! in the middle. The light is on permanantly in the last few days. i've check brake fluid and oil etc but they are all ok. if i take it the local Lexus garage, they'll charge £100 just to take a look. any help appreciated. I had all the brakes replaced in November 2007. thanks