I get this message on the window above my inspection panel, and have checked and replaced all my tail light/brake light bulbs with oem parts even though they were all operational, checked and cleaned the fuses, as well as all the wiring connecions to the bulb sockets. The master cylinder fluid level is fine too, but each time I step on the brake pedal, this message appears. It is my wife's '91 735i, and otherwise problem-free. Any suggestions?