Seems to turn on going over 45mph. No codes. ONLY the traction control light blinks/beeps. No check engine, abs, brake, etc lights on. Goes away when coming to a stop.
Trouble codes will be set when it thinks it isn't working right. But when it thinks it's just doing its job and controlling traction, that won't set trouble codes. A scan tool that shows you the "ABS History" will show what all the sensor readings were the most recent four times the ABS or traction control activated. That information can give you a big hint where the problem is.
Well Toyota recently replaced the axle. I wonder if they put the axle in without removing the ABS sensor. I think on some cars, including the Prius, it will break it if you don't take it out first. But generally when I've accidentally done that myself, the ABS light comes on too.