Lexus Repair: Brakes or ABS systems, toyota specialist, toyota avalon

Question
Dear Charles
Hello, I'm having a problem with my left front wheel.  Last spring while on a tollway going approximately 70 miles an hour I had to come to an abrupt stop due to traffic,causing a odd sound from the left front wheel , like" thud"! Driving all summer and into the fall, I have no problems whatsoever until this winter.  When there is ice or snow on the road and I applied the brakes there is a loud grinding, scraping noise from the left front wheel.  In my past experience with antilock brakes driving on a slippery road in applying the brakes it would seem that different wheels would lock intermittently!
My vehicle is a 2001 Toyota Avalon with 54,643 miles on it.  The ABS stay off except when you first turn the key on in the car.  I had the front brake pads replaced at the advise of a mechanic.  But to no avail.  Any advice you can offer will be greatly appreciated.I know you're listed as a Lexus specialist, but the Toyota specialist are all maxed out...

Phil
PS

Answer
ABS SYSTEMS DETECT WHEEL SPEED DIFFERENCE BETWEEN ALL FOUR WHEELS. IF A WHEEL HITS ICE AND THE BRAKES ARE APPLIED. THE ABS SYSTEM WILL PULSATE THE BRAKE ON THAT WILL IN AN ATTEMPT TO KEEP IT FROM SLIDING.
THIS A KIND OF ODD CONDITION. IS THE ABS LITE ON CONSTANTLY WHEN DRIVING NORMALLY? WHEN THE ABS IS ACTUATED THE LITE WILL FLASH AND BEEP. DOES IT HAPPEN? THERE MAY BE A CODE STORED IN THE DIAGNOSTIC SYSTEM THAT MAY LEAD YOU TO THE PROBLEM. I WOULD TAKE THE VEHICLE TO A TOYOTA DEALERSHIP SO THEY CAN DO A MORE INTENSE DIAGNOSIS. IT WOULD ALSO HELP THEM IF THEY CAN DUPLICATE THE CONDITION.
GOODLUCK PHIL