2001 Toyota Prius STEERING WHEEL SHAKES

The steering in Prius has electric power assist. There is a torque sensor in rack&pinion unit where attaches to steering column. This torque sensor detects difference in upper column rotation compared to below sensor rotation, sends info data to ECU and ECU sends signal to assist motor as to which direction and how much boost is required.
The sensor is (and this is the bad news) not a spare part (YET). It is part of the rack&pinion(about $1400DUS). If anyone has figured out how to repair and/or replace just the sensor there are a couple hundred people that would like to know. Myself included.
The good news is I don't think this problem will ever leave you stranded, just frustrated, angry etc.