I just bought a used Prius. The XM is active. I have no traffic on Nav though. Is this because the XM subscription does not have traffic on the account? BTW, I HATE XM traffic. It's horribly inaccurate in Austin, Texas. FM is MUCH better and free!
I think you need to launch the Toyota Entune app on your smartphone, then select traffic messages under destination in nav on your head unit, and it should connect through your Bluetooth smartphone.