Problem with car

The dash Icon you describe is for the traction control system. If the road surface is wet or uneven and you deliberatly floor the gas pedal or perhaps have one wheel in sand and the other on dry firm road surface the traction control takes over to prevent slip and the light flashing and buzzer is there to alert the driver that the road surface is wet or treacherous. There is one technical service bulletin from Scion about calibrating tthe system if parts are changed but nothing else relevant to worry about. What you ask about may be normal but the system can be diagnoised using a scan tool plugged into a 16 pin diagnostic plug under the driver's side of the dash.

usually happens when the tires are going bald if you're on dry even road when it happens