I am in the middle of a troubleshooting this 2006 Toyota Prius, with 200,000miles. I have used techstream to find that the B2271 and B2274 Hold acc monitors are giving issues. I have looked at all fuses and wires and it seems everything is fine. The power windows don't work. but interior lights do. headlight works brake lights work battery is good, hybrid and 12v I have checked just about everything other then changing the power source control ecu. I was following another thread made in 2015 and there was the identical issues, but there was no conclusion in the thread. i buy sell and export prius, I been a mechanic for 25 years, I have owned over 40 of these cars and never seen or not been able to figure one out.
No 'ON' No power No start but headlights, brake lights and interior lights work. Not sure how the power windows fit the equation (no wiring diagram with me). Sounds similar to symptoms of the AM2 fuse being open. If this is the case, it's usually caused by the inverter cooling water pump failing electrically.
when the power windows don’t work it concerns with the acc unit , but I’m not finding any faults. I’m so deep into this, 1 min in the fuses and pump were checked
It's been a while, but there was a thread on here with similar symptoms (iirc) and in the end swapping the power source ecu solved the problem. I don't have time right now to look for it, but those ecus are a dime a dozen from a salvage yard. Guess I did have time. Check out this thread: 2005 prius will not start but 12v battery seems to be working | PriusChat
Yes this seems to be identical: , the only difference is my engine light flashes when I press power and goes off . everything else is spot on, I’ll change the power ecu and go from there I’ll report back if it worked or not I read that you had removed the am2 fuse I think and you replicated the same conditions , which led you to believe the power control ecu had broke .
Went through some diag and fixed her up ! She is back to normal omg the power control unit seem to have went bad somehow