ABS Pulses on 1999 Lexus RX300

129,000 miles, ABS light comes on and pulses when ever brakes are applied no matter what the road conditions. AT highway speed the light comes on with out using the brakes. once I slow to city driving again the light goes out.

Asked by for the 1999 Lexus RX300
The ABS light is coming on because one of your wheel speed sensors is failing. If it reads "0 mph" when the rest of your sensors are at 25-30 mph, for example, the module thinks one of the wheels are locked up, and operates the ABS system pump motor in turn. Have the wheel sensors checked.