yeah that sounds pretty rare to have all 3 be defective at the same time, but i suppose it's possible ;o)

ok, well if you have the diode board covered and it is ok, then my only other educated guess would be the steering wheel angle sensor, but that's a long-shot being it 'should' only affect one side or the other and not both at the same time if it were out of center. (theoretically anyway) :o)